UK ISSN 0032–1400

PLATINUM METALS REVIEW

A Quarterly Survey of Research on the Platinum Metals and of Developments in their Application in Industry www.matthey.com and www.platinum.matthey.com

VOL. 47 OCTOBER 2003 NO. 4

Contents

Platinum Alloys for Shape Memory Applications 142 By T. Biggs, M. B. Cortie, M. J. Witcomb and L. A. Cornish

Searching at the European Patent Office 156

Automotive Exhaust Emissions Control 157 By Martyn V. Twigg

Precious Metal Recovery from Spent Catalysts 163 By Piers Grumett

Hydrogen Economy Forum in Russia 166 By F. A. Lewis

The Discoverers of the Iridium Isotopes 167 By J. W. Arblaster

Recyclable Microencapsulated Osmium Tetroxide Catalyst 174

Bicentenary of Four Platinum Group Metals 175 By W. P. Griffith

Magnetic Field Effects on Benzene Photodegradation 183

Abstracts 184

New Patents 188

Indexes to Volume 47 191

Communications should be addressed to: The Editor, Susan V. Ashton, Platinum Metals Review, [email protected] Johnson Matthey Public Limited Company, Hatton Garden, London EC1N 8EE Platinum Alloys for Shape Memory Applications

By T. Biggs 44 Kildonan Crescent, Waterdown, ON, L0R 2H5, Canada; E-mail: [email protected] formerly at Mintek

M. B. Cortie Institute for Nanoscale Technology, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia formerly at Mintek

M. J. Witcomb Electron Microscope Unit, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa and L. A. Cornish School of Process and Materials Engineering, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa now at the Physical Metallurgy Division, Mintek, Private Bag X3015, Randburg 2125, South Africa

Shape memory alloys (SMAs) are materials that can change their shape at a specific temperature and are used in applications as diverse as sensors, temperature sensitive switches, force actuators, fire-safety valves, orthodontic wires, fasteners, and couplers. The possible advantages offered by platinum-based SMAs involving the metals: iron, aluminium, gallium, titanium, chromium, and vanadium, are considered here and the likely systems upon which such alloys might be based are assessed. It is suggested that the most promising candidate systems are

ternary-alloyed variations of the Pt3 Al and PtTi phases, although SMAs based on PtFe3 have potential for low temperature applications. It appears possible to engineer a shape memory transition in the (Pt, Ni)Ti system anywhere between room temperature and 1000°C, a versatility which is probably unique among all known SMAs.

Metal alloys that can ‘remember’ their previous peratures for applications such as in jet engines, for shape and return to it when required are known as example to switch or modulate fluid flows of vari- shape memory alloys (SMAs). A ‘two-way SMA’ is ous sorts as the temperature changes, using one that can alternate repeatedly between two dif- SMA-operated valves. ferent shapes, whereas a ‘one-way SMA’ will change For these reasons, the authors embarked on a shape once and remain in that form. There are study of platinum-based (Pt-based) candidates for technological applications for both types of SMAs. SMAs as it was anticipated that they might have Commercial SMAs based on nickel-titanium (Ni- both good biocompatibility and a wider tempera- Ti) or copper-aluminium-zinc (Cu-Al-Zn) were the ture range of operation. first to be developed and gain popularity. However, these alloys can only be used up to ~ 100°C. Shape Memory Displacive Transformations One of the interesting areas of application for In very broad terms, there are two types of SMAs is in the medical field in the form of in vivo phase transformation in the solid state. In the first, implants, but neither Ni nor Cu is particularly bio- atoms diffuse and reposition themselves into a compatible. In addition, there is interest in new phase in a relatively independent fashion, each developing SMAs that can be used at higher tem- individual atom moving randomly. In the other

Platinum Metals Rev., 2003, 47, (4), 142–156 142 (a) (b)

Fig. 1(a) The DOc¢ unit cell (blue) of the Pt3Al tetragonal structure (low temperature). It contains a distorted f.c.t. lattice which is also shown in (b). The Pt atoms (white) lie slightly offset from the centre of the faces and the Al atoms (black) sit at the corners of the cell. In (b), for clarity, only the Pt atoms on the top and front faces are shown type of transformation, whole rows of atoms shear ing the transformation of the high temperature or displace together, each atom moving in the b-b.c.c. and the a-f.c.c. phases as the most likely same fashion as its neighbours, to produce a sig- for the development of Pt-based SMAs. nificant increment of the new phase in an instant. The latter type of solid state phase transformation Displacive Transformations is known as displacive. A displacive phase trans- in Pt Alloys formation in the alloy system is a prerequisite for Pt alloy systems that are known to undergo dis- SMA behaviour. However, displacive transforma- placive transformations are described below. The tions have not been extensively studied in transformations of each system will be examined. Pt-based systems. This paper explores displacive transformations Pt-Fe in some Pt systems and proposes systems that One of the best documented martensitic trans- might have potential for future development as formations in Pt-based systems is that of PtFe3. SMAs. Pt-Fe alloys containing about 25 at.% Pt undergo A variety of different definitions and classifica- an order-disorder transformation (2, 3). The disor- tions of displacive transformation exist, of which dered alloy has a f.c.c. structure and undergoes a the martensitic transformation is a particular sub- martensitic transformation to a b.c.c. structure at class (1). Martensitic transformations are defined around room temperature (4). Alloys containing in terms of their very particular crystallographic more than 25.5 at.% Pt are also reported to trans- properties, and are considered to be the best basis form martensitically from a disordered f.c.c to a for developing a shape memory effect. Delaey (1) b.c.t. (body centred tetragonal) or alternatively to a proposed that they can be subdivided into three f.c.t. structure, depending on composition. main types: Wayman (5) reported that no shape memory • allotropic, effect was observed in the disordered or partially

• b-b.c.c. (body centred cubic) Hume Rothery ordered parent phases of PtFe3, but that after and Ni-based SMAs, and ordering, the martensite transformation becomes • a-f.c.c. ® f.c.t. (a-face centred cubic to face thermoelastic, proceeding from f.c.c. to b.c.t. and centred tetragonal). back again, as many times as desired (6–8). The allotropic option is not possible for Pt, leav- Accompanying the increase in ordering is a drop in

Platinum Metals Rev., 2003, 47, (4) 143 Fig. 2 For the Ti-Pt system, the crystal structure of parent and product TiPt phases (after Otsuka and Ren (13)). The parent is a B2 structure at high temperatures and transforms to an orthorhombic B19 structure at lower temperature. The Ms temperature is ~ 1000ºC

the M s (the martensite start transformation tem- Pt3Al and Pt3Ga undergo a phase change from g¢, perature). It has been proposed by Muto et al. (4, 9) a high temperature cubic (L12) structure, to g2¢, a that the f.c.c. to b.c.t. and the f.c.c. to f.c.t. trans- low temperature tetragonal (DOc¢) structure, see formations are independent and competitive. The Figure 1. Some workers (10, 11) have reported the transformation temperature is very sensitive to existence of an intermediate phase, g1¢, (DOc) changes in the composition and degree of order of although its existence is uncertain. The consecutive the alloy. Oshima et al. (6) observed that the recov- transformations of g¢ ® g1¢® g2¢ are reported to erable strain by the shape memory effect is small in be martensitic in nature (10). The Pt-Al martensite the f.c.c. to f.c.t. transformation (< 3%). Larger phase transformation occurs in the region 73 to 78 strains would be more desirable in SMAs. at.% Pt, and M s is reported £ 1300°C (12), and The 24 at.% Pt-Fe alloy is very hard and brittle, between room temperature and 350°C by others but ductility increases with increasing Pt content. (10). For Pt-Al, at higher Pt contents, a Pt-rich

The PtFe3 system has some very interesting prop- solid solution exists which forms a eutectoid mix- erties (such as a potential for magnetic-induced ture with the tetragonal Pt3Al phase. At least two, shape changes) and is worth exploring further. rather different, versions of the Pt-Al phase dia-

However, its Ms temperatures are too low to meet gram have been published (10, 12). the requirements of either a medical in vivo applica- tion or of a combustion engine. Therefore, it will Pt-Ti, Ni-Ti, Pt-Ti-Ni not be considered here. A martensite transformation has been reported in the Pt-Ti system at around 50 at.% Pt. It is a dis- Pt-Al, Pt-Ga placive transformation from a cubic (B2) high A martensite-type transformation has been temperature structure (b-TiPt) to an orthorhombic reported in both the Pt-Al and Pt-Ga systems. At (B19) structure (a-TiPt) at low temperatures, see around 75 at.% Pt, the intermetallic compounds Figure 2, and has an Ms in the region of 1000°C.

Platinum Metals Rev., 2003, 47, (4) 144 The cubic to orthorhombic transformation in this B2 b.c.c. parent phase, which suggests that the alloy is associated with a smaller temperature hys- nature of the high temperature phase in this sys- teresis than occurs, for example, for the cubic (B2) tem justifies another investigation. Twinning was to monoclinic (B19¢) transformation in the well- observed, but it was concluded that, while this known NiTi SMA (known as Nitinol), which has could have arisen from a martensite transforma- an M s in the vicinity of room temperature (13). tion, it was most likely to have been formed by an The Ms in PtTi is a maximum at 50 at.% Pt and order-disorder transformation. decreases as the Pt content varies on either side. Although in NiTi the transformation would nor- Experimental Investigations mally go from B2 to B19¢, it may, depending on Screening Pt-X Binary Systems for Alloys alloy composition, do so via an intermediate Little further information, other than that men- rhombohedral (R) phase, or, if Pt is alloyed with tioned above, has been published on Pt systems, the NiTi, via an orthorhombic (B19) phase. and as there may be many other systems with the Depending on the composition, the reaction potential to be developed into SMAs, the authors might not proceed any further, so the final prod- screened the literature on binary Pt alloy systems, uct could be orthorhombic. Lindquist (14) has using the following criteria: investigated the substitution of up to 30 at.% Pt [1] The crystal structures of parent and product for Ni in NiTi, and found that the alloys exhibited intermetallic phases were used as the primary dis- the one-way shape memory effect. An initial criminant. A displacive transformation implies decrease in M s was noted, but thereafter an that there is a crystallographic relationship increase in M s with increasing Pt content was between parent and product phase, and there are reported. As a smaller temperature hysteresis is several known combinations of parent and prod- associated with the B2 to B19 transformation than uct phase structures that satisfy this requirement. the B2 to B19¢ transformation, this would affect Sometimes information was available on only one the range of applications of a shape memory alloy. phase, but if there seemed any possibility, based on the crystal structure, of a displacive transfor- Pt-Cr mation, the system was considered. Twinned microstructures have been observed [2] The transformation temperatures were in the 50 at.% Pt-Cr system by Waterstrat (15). assessed as the second criterion. Only alloy sys-

The presence of twins could be due to a number tems likely to have an Ms above room temperature of reasons: for instance, a displacive transforma- were studied further. tion, ordering, etc. Transformation from a [3] The presence of twins or laths in the disordered cubic structure to an ordered tetragonal microstructure was the next criterion. While the structure occurs at ~ 1100°C, although dilatome- presence of twins or laths does not prove that a try did not provide evidence for a displacive martensite transformation has occurred (these fea- transformation (15). tures arise from a variety of phenomena, such as ordering), their absence was taken as an indication Pt-V that a displacive transformation had probably not The 50 at.% Pt-V alloy has an orthorhombic occurred. Again, this is not an infallible method, as structure (B19) at room temperature (16), ostensi- twins or laths may be present, but may not have bly transforming to a high temperature f.c.c. phase been exposed by the experimental technique (based on the AuCu structure, that is, an ordered utilised. For example, in the Pt-Al system it was

L10 f.c.c. structure) at ~ 1500°C (17). However, essential to polish the samples with colloidal silica Waterstrat (16) who examined this system some 14 so as to image twins by scanning electron micros- years earlier, did not record this. In fact, in most copy (SEM). The lack of twins was, however, used displacive transformations a low-temperature B19 to eliminate systems and to narrow down the pos- phase is generally coupled with a high temperature sible systems going for further investigation.

Platinum Metals Rev., 2003, 47, (4) 145 [4] The final criterion deemed important was duc- materials) (18) and Crystallographica (a software tility: only ductile alloys were selected. Hardness, package) (19) were utilised in order to model lat- while not always being a perfect guide to ductility, tices and predict the corresponding X-ray spectra. was used as an indicator (some alloys could be hard The modelling gave additional information regard- and yet still be sufficiently ductile). Alloys were ing peak shapes as well as enabling the angular also cold rolled to estimate the degree of ductility. range to be extended beyond that of the JCPDS Alloys that cracked on the first rolling pass were database thus allowing better comparison with the immediately eliminated from the study. experimental data. In order to decide whether a transformation is Samples were polished to a 0.25 mm finish, and displacive, the relationship between the high-tem- some were further polished using colloidal silica. perature parent phase and the product phase needs Samples were etched for varying times with a to be examined. This was often difficult as the par- warm solution of 50% aqua regia (3:1 hydrochloric ent phase was frequently only stable at exceedingly acid : nitric acid), 50% water. Examinations were high temperatures, and more detailed work, includ- performed by SEM. Elemental analysis was under- ing high temperature X-ray diffraction (XRD) and taken using energy dispersive X-ray spectroscopy transmission electron microscopy (TEM), would (EDS) and pure element standards. need to be conducted before the true nature of a Differential thermal analysis (DTA), with scans phase change could be determined. However, pre- taken in an argon atmosphere between 25 to liminary conclusions were made based on 1500°C, was conducted at heating and cooling rates morphology and on the crystallographic relation- of ~ 5°C min–1. Each sample was repeatedly cycled ships. At this stage, the aim of the investigation from room temperature up to 1200 or 1500°C if no was merely to find some systems that might exhib- melting was anticipated. Some samples also under- it displacive transformations and that could have went differential scanning calorimetry (DSC) commercial application in the medical and high between 20 to 1395°C at a rate of 10°C min–1. temperature fields. Ternary phase diagrams ought to be based on quenched samples but due to experimental con- Sample Manufacture and Characterisation straints this was not possible, so diagrams of the Alloy samples (1–3 g buttons) were prepared by phases present after furnace cooling are presented. arc-melting the individual elements into a button This has some merit as some of the final systems under an argon environment, on a water-cooled proposed here, either as possible SMAs or worthy of copper hearth. Buttons were melted three times to further study, would probably have to employ fur- ensure mixing. In most instances, samples were nace cooling if commercialisation were to be first examined in the arc-melted state. They were considered. subsequently solution treated to be wholly within the parent phase field, for periods of 3 days to a Alloy Screening Results week, at 1200 or 1350°C for the Pt-Ti- and Pt-Al- Detailed results of the initial screening are based alloys, respectively, followed by furnace reported elsewhere (20). Numerous Pt alloys were cooling. The alloys were then subjected to various selected, based on the initial criteria, and then further heat treatments. examined. Systems excluded from further study Alloy hardness was evaluated on a Vickers were: hardness indenter with either 5 or 10 kg loads. At • Pt-Fe: the transformation temperatures are least six (and generally ten) indentations per sam- below room temperature. ple per condition were performed, and an average • Pt-Cu and Pt-Mn: both showed twins, but the is reported. results were not sufficiently encouraging or repro- XRD data were gathered from the alloys, and ducible to merit investigation at this stage. the JCPDS database (the International Centre for • Pt-Cr and Pt-V: both displayed twinning but Diffraction Data’s database of spectra of all known the alloys cracked on the first pass of rolling.

Platinum Metals Rev., 2003, 47, (4) 146 Fig. 3 Scanning electron micrograph, backscatter mode, showing the 75.1 at.% Pt-Al sample, after heat treatment at 1350ºC for 3 days and furnace cooling. Tetragonal Pt3 Al structure

However, the Pt-Al and the Pt-Ti systems both Mishima et al. (10) proposed that the phase field appeared to have the necessary prerequisites and changed from (cubic Pt3Al + (Pt)) to (tetragonal were therefore studied in greater detail on their Pt3Al + (Pt)) at ~ 340°C, whereas Massalski pro- own, and with ternary additions of Ni and ruthe- posed that this change was at 1280°C (17). In fact, nium (Ru). The results are discussed below. samples in the region 74.6 to 85.9 at.% Pt were found in this work to have transformations in the Pt-Al range 132 to 137°C, see Figure 4. Samples containing 68 to 85 at.% Pt were stud- The transformation temperature was very sensi- ied. Arc-melted samples often had dendritic tive to composition and, as the Pt content increased microstructures that were not completely removed from 74.6 to 75.7 at.% Pt, the transformation tem- by heat treatment. Samples of composition 68 to perature increased from 132 to 308°C. The 85.9

73.9 at.% Pt contained the cubic Pt3Al phase, while at.% Pt sample was a eutectoid mixture of Pt3Al + the arc-melted 68.8 at.% Pt sample also contained (Pt) with a transformation temperature ~ 337°C. the Pt2Al phase. There was no evidence of twin- These transformation temperatures were more con- ning in samples in this range (68 to 73.9 at.% Pt). sistent with the phase diagram of Mishima et al. (10) Samples containing 71 to 73.9 at.% Pt were all than that of Massalski (17). single phase (cubic Pt3Al), while those in the 74.6 to 76.6 at.% Pt range contained a phase identified by XRD as the tetragonal Pt3Al phase. This phase was twinned, as shown in Figure 3. Samples in the 76.6 to 87.9 at.% Pt range com- prised a eutectoid mixture of the tetragonal Pt3Al phase and the Pt-rich solid solution phase. The eutectoid point was at about 80.6 at.% Pt. Twins were generally observed in the tetragonal Pt3Al phase. The high temperature phase fields were general- ly consistent with the phase diagram of Massalski (17). Attempts were made to measure the phase transformation temperatures and DSC proved to be more successful than DTA as the enthalpy changes Fig. 4 Comparison of phase transformations detected in Pt3Al by DSC and/or DTA in the present work, with were very small, resulting in very small peaks. those reported previously by Mishima et al. (10)

Platinum Metals Rev., 2003, 47, (4) 147 Fig. 5 Proposed isothermal section for Pt-Al-Ru at 1350°C (held at this temperature for 3 days followed by furnace cooling). Phase fields are indicated. LT denotes the low temperature form (tetragonal)

Hardness measurements were conducted to Ternary additions, using Ru or Ni, were then con- gain some idea of the mechanical properties. The sidered as a means to gain more control over the measurements were found to depend on stoi- transformation by altering phase fields and stabili- chiometry, varying between 350 to 650 HV10. ties. Minimum hardness occurred at around 75 at.% Pt. However, the still relatively high hardness of the Pt-Al-Ru

75 at.% Pt alloy (350–400 HV10) suggested that the Ru was selected as a ternary alloying option as alloy might be difficult to work. Since all the other up to 40 at.% Ru dissolves in the Pt solid solution alloys were harder, it was felt that all the Pt-Al alloy in the Pt-Ru system. A range of Pt-Al-Ru samples range in this study might be difficult to work. was investigated, containing between 5 and 20 at.% Nevertheless, limited amounts of cold rolling Ru, and a nominal Al content of 25 at.%. The proved feasible, and the 75 at.% Pt alloy could be intention was to substitute Ru for Pt in Pt3Al. The reduced by 18% (it hardened to 457 HV10) before effect of Ru on the phase stability is best illustrat- cracking occurred. With appropriate thermome- ed in a proposed isothermal section shown in chanical treatment, our experience suggests that Figure 5. this alloy could be worked further. It was deduced For low additions of Ru and high Pt, a mixture that hot rolling could also be a possible processing of Pt3Al and a Pt-rich solid solution (f.c.c.) con- route. While the Pt-Al transformation was marten- taining Ru was observed. The Pt3Al matrix was sitic in nature, the phase transformation was only generally twinned, see Figure 6, suggesting it was observed in a narrow composition range and M s the tetragonal Pt3Al phase. In samples where the was exceedingly sensitive to the chemical composi- (Pt) phase was present in a Pt3Al matrix, heat treat- tion of these button samples. ment at 1350°C resulted in the (Pt) solid solution These features make Pt-Al an unlikely candidate phase decomposing into smaller, very fine, for commercial application as a binary alloy. spheres. This heat treatment also caused the Ru to

Platinum Metals Rev., 2003, 47, (4) 148 Fig. 6 Optical micrograph of the 74.1 Pt-22.6 Al-3.3 at.% Ru sample, after arc-melting and etching with aqua regia. The twinned microstructure (tetragonal Pt3 Al) can be clearly seen

diffuse out of the matrix and into the Pt-rich solid cubic-to-tetragonal transformation of Pt3Al. For solution. For larger additions of Ru, a mixture of additions of less than 4 at.% Ru, a transformation cubic Pt3Al and a h.c.p. (hexagonal close packed) temperature of about 350°C was indicated for the Ru-rich solid solution containing Pt was observed, cubic-to-tetragonal change. The transformation see Figure 7. After heat treatment, there was min- temperature (at which the transformation imal Ru dissolved in the Pt3Al matrix and minimal occurred) was difficult to measure accurately Al in the Ru-rich solid solution. because the enthalpy changes were very small. The hardness of all the samples was in the The results suggest that the addition of Ru did range 425 to 618 HV10 showing that adding Ru not much extend the composition range of the increased the hardness considerably. Also, the parent Pt3Al phase. The appearance of cubic Pt3Al addition of at least 4 at.% Ru suppressed the at room temperature in the samples with the high- er Ru additions reflects that the tielines join h.c.p.

(Ru) and cubic Pt3Al, rather than the tetragonal form. This means that there is at least one invari- ant reaction involving the terminal solid solutions,

(Ru) and (Pt), and the two forms of Pt3Al.

Pt-Al-Ni Nickel has been considered as a partial substi- tute for Pt (at least for non-medical applications) due to its similarity in metallurgical properties and its far lower cost. The region of present interest, in the Pt-Al-Ni ternary diagram (21), is dominated by

the PtAl, tetragonal Pt3Al and (Ni, Pt) phases. However, there is an inconsistency between this ternary phase diagram and existing binary phase diagrams (10, 17) in that the ternary section does

not show a cubic Pt3Al phase. Heat treated samples in the Pt-rich end of the isothermal section, as well as samples containing Fig. 7 Scanning electron micrograph, backscattered only the Pt3Al phase were targeted, and the results mode, of the 50.6 Pt-22.1 Al-27.3 at.% Ru sample after are summarised in the proposed isothermal sec- arc-melting. The light matrix is Pt3Al and the dark phase (needles + fine dark phase) is the Ru-rich solid solution tion at 1350ºC for Pt-Al-Ni, see Figure 8. The

Platinum Metals Rev., 2003, 47, (4) 149 Fig. 8 Proposed isothermal section for Pt-Al-Ni at 1350°C (held at this temperature for 3 days followed by furnace cooling). Phase fields are indicated. LT designates the low temperature form, (tetragonal)

samples in the Pt-rich end of the isothermal sec- 46 at.% Pt, the Ti4Pt3 and TiPt phases coexisted. tion, consisted of a mixture (eutectic or eutectoid) The TiPt phase has a wider stability range, unlike of Pt3Al and (Pt). As the Pt content increased, the the other phases, and is stable between 46 and 55 amount of the Pt3Al phase diminished. The results at.% Pt. It occurs in a low temperature form (des- show that there is a mixture of tetragonal Pt3Al and ignated a-TiPt) with B19 orthorhombic structure, (Pt) in the Pt-rich end of the Pt-Al-Ni section and and in a high temperature form above ~ 1000°C, a cubic Pt3Al and (Pt) mixture at lower Pt contents. (b-TiPt) with the B2 b.c.c. structure.

The tetragonal Pt3Al phase underwent a displacive The b-TiPt structure cannot be preserved down transformation. Nickel partitioned preferentially into to room temperature by quenching since it under- the Pt-rich solid solution, but addition of Ni also goes a martensitic transformation to a-TiPt on extended the cubic Pt3Al phase field into the ternary. cooling. The b-TiPt « a-TiPt transformations are Many phases formed in the Pt-Al-Ni system complex and, just like those in NiTi, take place via

(21). In addition to the Pt3Al and Pt phases, a one or more intermediate structures (22). In the

NiPt2Al (Heusler phase) and a twinned phase (not region 55 to 63 at.% Pt, both the TiPt and the

Pt3Al) were observed (20). The transformation Ti3Pt5 phases were observed. Further discussion temperatures were not detectable using either on phase relations in the Pt-Ti system, including DTA or DSC. Hardness values ranged from 257 to DTA studies which suggested complex phase rela-

624 HV10 depending on the phases present. tions, can be found elsewhere (20, 22). The morphology of the a-TiPt phase was Pt-Ti dependent on the cooling rate. Figure 9 shows a Samples of Pt-Ti containing 30 to 61 at.% Pt typical lath-like structure observed in samples that were examined. A two-phase region of Ti3Pt and were cooled rapidly. Figure 10 shows a finer

Ti4Pt3 (nominal stoichiometry) was observed twinned structure obtained after furnace cooling. between 30 and 43 at.% Pt, while between 43 and The a/b transformation temperature for the TiPt

Platinum Metals Rev., 2003, 47, (4) 150 Fig. 9 Optical micrograph of a 49.5 at.% Pt-Ti sample, after heat treatment at 1200°C for 2 hours, followed by water quenching. The lath-like a-TiPt phase is visible after etching with aqua regia

phase varied from 950 to 1050°C, and was a max- perature SMA, with a transformation temperature imum at the stoichiometric composition and of ~ 1000°C. However, a means to reduce this decreased on either side of it. The minimum hard- temperature, and a better level of oxidation resis- ness occurred at the stoichiometric composition. tance, would be very helpful. For these reasons, The slower cooled samples (furnace cooled) were the addition of ternary elements to Pt-Ti was then softer than faster cooled samples (water quenched investigated. or arc-melted). A furnace-cooled 50 at.% Pt-Ti sample was the softest, with a hardness value of ~ Pt-Ti-Ru

250 HV10, and could be cold rolled to ~ 50% The phase fields proposed for the heat-treated reduction before cracking occurred. The sample samples are given in Figure 11. The Pt-Ru system was also hot rolled at ~ 1100°C to a reduction of consists of terminal Pt-rich and Ru-rich solid ~ 90%, although oxidation was observed. solutions, and a two phase mixture in the region The stoichiometric TiPt composition appears 62 to 80 at.% Ru. In the Ru-Ti system from 45 to offer a good prospect for a workable high-tem- to 53 at.% Ru, a B2 TiRu phase is observed. The

Fig. 10 Optical micrograph of a 53.8 at.% Pt-Ti sample, after heat treating at 1200°C for 1 week, followed by furnace cooling. The finely twinned a-TiPt phase is visible after etching with aqua regia

Platinum Metals Rev., 2003, 47, (4) 151 Fig. 11 Proposed isothermal section for Pt-Ti-Ru at 1200°C (held at this temperature for 3 days followed by furnace cooling). Phase fields are indicated

terminal Ti-rich solid solution is b.c.c. at elevated tial isothermal section in Figure 11. The TiRu (B2) temperatures, undergoing an allotropic transfor- phase was noted to extend into the ternary up to mation to h.c.p. on cooling. about 15 at.% Pt. Thus, the two phases do not Alloy samples investigated included ones in form a continuous field, despite sharing a common which Pt was fixed at 50 at.%, with Ru varying structure. from 5 to 20 at.% Ru, as well as samples that were anticipated to be in phase fields surrounding TiRu Pt-Ti-Ni or TiPt. Samples in the arc-melted state were gen- The addition of Ni to TiPt was also investigat- erally cored and had to be heat treated at 1200°C ed for the same reasons as in the Pt-Al-Ni system. for 3 days to obtain a reasonably homogeneous Nitinol (NiTi) is a well-known commercial SMA microstructure (23). and some work has already been done on the sub- The addition of 5 to 10 at.% Ru led to a stitution of Pt for Ni (24, 25). These studies decrease in the TiPt transformation temperature concentrated on low additions of Pt (up to 30

(Ms decreased from ~ 1000°C to ~ 700°C, while at.%) and suggested that Pt-Ti-Ni alloys would the hysteresis increased). The enthalpy change also show usable shape memory properties, but there decreased. These properties will affect the poten- were problems with formability (25). tial areas of application and determine whether The present work investigated a range of alloys small additions of Ru are desirable. For coupling and two rather different heat treatments. These applications, a large hysteresis would be desirable, were a homogenising heat treatment at 1200°C for whereas for actuator applications, a small hystere- 3 days followed by furnace cooling, and a solution sis may be preferable. anneal heat treatment at 1200°C for two hours The addition of Ru extended the TiPt phase followed by a water quench. The results are sum- field into the ternary diagram at least up to 19 at.% marised in a proposed partial isothermal section in Ru. The results are summarised in a proposed par- Figure 12. Nickel stabilised the a-TiPt extending it

Platinum Metals Rev., 2003, 47, (4) 152 Fig. 12 Proposed isothermal section for Pt-Ti-Ni at 1200°C (held at this temperature for 3 days followed by furnace cooling). Phase fields are indicated

up to 18.8 at.% Ni into the ternary field. Further a single phase a-TiPt. Samples containing higher details are available elsewhere (20, 26). Ni contents contained an additional lath-like

Samples containing 5 to 20 at.% Ni (substitut- phase; XRD suggested this was possibly ~ Ti3Pt5. ing for Pt in TiPt) were cored after arc-melting and There was also a third phase, rich in a light element had to be heat treated to homogenise the or elements (indicated by low EDS totals), which microstructure. If these alloys were to have com- was probably a Ti oxide. mercial application, this would be a required The effect of Ni on the transformation temper- processing step. Samples containing about 50 at.% ature is given in Figure 13. The addition of up to Ti and up to about 5 at.% Ni consisted mainly of 50 at.% Ni led to a decrease in transformation

Fig. 13 The effect of Ni on the TiPt transformation temperature (reported and experimental). Some of the results of Lindquist and Wayman (25) are included for comparison

Platinum Metals Rev., 2003, 47, (4) 153 temperature from nearly 1000°C to room temper- the differential in price of the raw material. ature. The apparent lack of influence from Ni at Therefore, Pt-based SMAs may be acceptable for low additions, and the variations in hardness some applications. observed in this range are more a consequence of As far as the existing base-metal SMAs are con- slight variations in Pt and Ti content among the cerned, it is interesting to review briefly their samples. At low Ni additions, the Pt and Ti con- shortcomings. Any Pt-based SMA that could solve tent have a greater influence on transformation one of these problems would have prospects for temperature (which is a maximum at about 50 at.% commercialisation. Pt), than the Ni content. Another important issue to consider is which Shortcoming of Current Base-Metal SMAs transformation is being monitored: B2 ® B19 · A first shortcoming of these materials is that (TiPt) or the B2 ® B19¢ (TiNi). In this study, the they are comparatively brittle, and therefore B2 ® B19 transformation was monitored. The expensive to convert into the desired form of wire samples containing Ni appeared to have lower or sheet. The lack of ductility follows directly on enthalpy changes. There was no observed signifi- from their ordered, b.c.c. crystal structures. There cant trend or change in hysteresis with Ni is a fundamental lack of slip systems and disloca- additions. The addition of 20.3 at.% Ni led to a tion mobility in such structures. Therefore, it is

Ms of 572°C and As (austenite start temperature) improbable that any Pt-based SMA, which as we of 620°C which compared favourably to prior have shown is also based on such alloy systems, measurements of 626 and 619°C, respectively, for would be fundamentally different. Nevertheless, a 20 at.% Ni addition (25). reasonable ductility for TiPt has been indicated.

Hardness values varied from 226 to 626 HV10 This alloy seems to be at least as ductile as the best for alloys in the Pt-Ti-Ni system, depending on the of current commercial SMAs, and thus it requires phases present and on the heat treatment. For only some other technological advantage to make samples containing the a-TiPt phase, the addition it a viable proposition. of Ni generally increased the hardness. As in the · A second shortcoming of most commercial binary study, the cooling rate significantly affected SMAs is that their working temperatures range the hardness with the furnace cooled samples from ~ 150 down to –200°C. Neither of the com- being the softest. The hardness was also affected mon systems (NiTi or Cu-based) is able to by the Ti content; for example, a sample of 10 at.% function as a SMA at elevated temperatures.

Ni could have a hardness from 398 to 626 HV10 as Furthermore, Cu-based systems have an intrinsic the Ti content varied around the stoichiometric problem with ageing, and undergo an associated point. The lowest hardness values were obtained at time-dependent change in properties. Therefore, around 50 at.% Ti (the balance is Ni + Pt). they must be protected from exposure to temper- atures much above 150°C. As we have seen, the Comparisons of SMA Materials Pt-based alloys offer the prospect of an enormous The case for a commercial Pt-based SMA can enhancement in operating temperatures, up to only be advanced based on some specialised and 1000°C. In a sense, this follows directly on from unique technological property or properties of suf- the far higher melting points of the parent com- ficient utility to overcome the initial cost of Pt. In pounds, although, other serendipitous factors such the absence of such an incentive, it would make as the high temperature of the TiPt B2-to-B19 more sense to use the existing base-metal SMAs. transformation also apply. A viable Pt-based SMA However, it should be noted that most SMA appli- for elevated temperature application seems a very cations are comparatively high-value in nature and real possibility. they use rather small SMA components. Thus, the · Another issue with existing commercial SMAs actual price differential between a Pt-based and a is their corrosion resistance, or lack of it. These conventional component is not nearly as large as materials are obviously optimised for shape mem-

Platinum Metals Rev., 2003, 47, (4) 154 ory effect and corrosion is very much a secondary orthorhombic (B19) at ~ 1000°C, which varied consideration. Nitinol is reasonably corrosion slightly with composition, but which did not resistant, but there appears to be some debate in appear to be a problem in terms of reproducibili- the literature regarding its long-term biocompati- ty. Figure 2 shows that this transformation occurs - bility (27, 28). There is no doubt that the Cu-based by a basal shear (111)[110] and a shuffle (13). DTA SMAs lack sufficient corrosion resistance for long studies by the authors suggest that this transfor- term in vivo applications. These issues offer an mation may be complex (20, 22). The 50 at.% opportunity for a Pt-based SMA, provided that it Pt-Ti alloy could be cold rolled to 50% reduction, possesses sufficient corrosion and oxidation resis- and was hot rolled to 90%, which showed it was tance for the given application. The high resistance workable. The alloy properties were strongly of Pt to corrosion and oxidation is, in our experi- affected by heat treatment, with the cooling rate ence, generally imparted in some measure to its playing the biggest role. Slow cooling resulted in alloys, which gives us a degree of optimism for the softest alloys, with a finely twinned microstruc- possible medical application of Pt-based SMAs. ture. · Finally, another shortcoming of commercial Ternary additions of Ni and Ru decreased the SMAs is that the strain range over which they transformation temperatures to ~ 600 and 700°C, operate is quite limited, and thus working devices respectively, but increased the hardness. The main have to be designed to use changes in strain of the disadvantage of the Pt-Ti-based systems (besides order of a few per cent. Any alloy that can show cost) was the tendency for oxygen contamination stable shape memory properties over greater strain and associated internal oxidation. ranges will have immediate applications. Regrettably, there is nothing to suggest to the Conclusions authors that any such breakthrough would be The most probable candidates from which to achieved in a Pt-based composition. develop commercial Pt-based SMA systems are

It should be noted that SMAs operating above Fe3Pt, Pt3Al and TiPt. In each case, commercial room temperature were targeted in this study, and alloys would also contain ternary or higher addi- this eliminated the Fe3Pt phase, which has a tions. The Fe3Pt alloys have working temperatures diverse range of interesting and technologically below room temperature, while both Pt3Al and relevant properties. TiPt have characteristics that suggest their use for The Pt-Al system at around 75 at.% Pt has a in vivo and elevated temperature SMA applications. phase transformation which occurs from 132 to The Pt-Al system (at around 75 at.% Pt) 337°C, depending on composition. This system is exhibits a displacive transformation from an both corrosion resistant and capable of withstand- ordered f.c.c. to ordered f.c.t. structure in the ing elevated temperatures. It exhibits superb range 132 to 337°C. It appeared to be rather sen- oxidation resistance (29). However, the transfor- sitive to compositional changes, and this might mation is exceedingly sensitive to compositional complicate its commercial application. changes which would make it a very difficult alloy The Pt-Ti-based alloys (at around 50 at.% Pt) to use commercially. Ternary additions of Ru did exhibit reproducible displacive transformations not appear to stabilise either parent or product from b.c.c. (B2) to orthorhombic (B19) that have phase. Nickel additions stabilised the parent phase the potential for high temperature shape memory

(cubic Pt3Al) but promoted the formation of some applications. Ternary additions of Ru and Ni, and Pt-Al-Ni phases which could complicate potential possibly other elements, can be used to reduce the applications. On balance, while it appears possible working temperatures to ambient, but this may be to develop these materials as SMAs, they do not at the expense of a loss of ductility. These pro- appear to be the best prospects. posed systems can also be modified by control The Pt-Ti system at around 50 at.% Pt has a over their stoichiometry and thermomechanical displacive transformation from b.c.c. (B2) to processing.

Platinum Metals Rev., 2003, 47, (4) 155 Acknowledgements 20 T. Biggs, “An Investigation into Displacive The authors would like to thank Mintek for supporting this Transformations in Platinum Alloys”, Ph.D. Thesis, work and for the use of their facilities. The differential scanning University of Witwatersrand, South Africa, 2001 calorimetry was conducted at the University of Cape Town by 21 “Handbook of Ternary Alloy Phase Diagrams”, eds. Prof. C. Lang and Dr J. Basson. This work was partially sup- P. Villars, A. Prince and H. Okamoto, ASM, ported by the FRD, now NRF. M.J.W. also thanks the Materials Park, OH, 1995, p. 4163 University of the Witwatersrand, via the Microstructural Studies 22 T. Biggs, M. B. Cortie, M. J. Witcomb and L. A. Research Programme, for financial support. Encouragement and Cornish, Metall. Mater. Trans. A, 2001, 32A, 1881 assistance from I. Klingbiel, J. Hohls, P. Ellis and V. Viljoen are 23 T. Biggs, L. A. Cornish and M. J. Witcomb, Proc. gratefully acknowledged. Microsc. Soc. South Afr., 1999, 29, 11 24 V. N. Kachin, Rev. Phys. Appl., 1989, 24, 733 References 25 P. G. Lindquist and C. M. Wayman, in “Engineering 1 L. Delaey, ‘Diffusionless Transformations’, in Aspects of Shape Memory Alloys”, eds. T. W. “Materials Science and Technology”, Vol. 5, “Phase Duerig, K. N. Melton, D. Stöckel and C. M. Transformations in Materials”, ed. P. Haasen, VCH- Wayman, Butterworth-Heinemann Ltd., London, NE, New York, 1991, pp. 341–402 1990, p. 58 2 D. P. Dunne and C. M. Wayman, Metall. Trans. A, 26 T. Biggs, L. A. Cornish, M. J. Witcomb and M. B. 1973, 4A, 137 Cortie, J. Phys. IV France, 2001, 11, Pr8-493 3 L. S. Benner, T. Suzuki, K. Meguro and S. Tanaka, 27 S. A. Shabalovskaya, Int. Mater. Rev., 2001, 46, (5), 233 “Precious Metals Science and Technology” based on 28 F. Widu, D. Drescher, R. Junker and C. Bourauel, Kikinzoku no Kagaku, the 100th Anniversary J. Mater. Sci: Mater. Med., 1999, 10, (5), 275 Commemorative Publ. of Tanaka Kikinzoku Kogyo 29 P. J. Hill, N. Adams, T. Biggs, P. Ellis, J. Hohls, S. S. K.K., Japan, Int. Precious Metals Inst., 1991, pp. 630–635 Taylor and I. M. Wolff, Mater. Sci. Eng. A, 2002, 4 S. Muto, R. Oshima and F. E. Fujita, Metall. Trans. A, 329–331A, 295 1988, 19A, 2723 5 C. M. Wayman, Scr. Metall., 1971, 5, 489 The Authors 6 R. Oshima, S. Muto, F. E. Fujita, T. Hamada and M. Taryn Biggs has worked as a research scientist at Mintek, South Sugiyama, ‘Shape memory alloys’, in Vol. 9, “Shape Africa, and as a post-doctoral fellow at the University of British Memory Materials”, eds. K. Otsuka and K. Shimizu, Columbia, Canada. Currently she is at Dofasco Inc., Ontario, Canada. Proc. Int. Symp. Mater. Res. Soc., Int. Mtg. on Adv. Her interests include texture, phase transformations, steel, aluminium, Mater., Tokyo, Mater. Res. Soc., Pittsburgh, PA, precious metals, metal composites and materials applications. 1989, pp. 475–480 Mike Cortie is Professor of Nanoscale Technology at the University 7 R. Oshima, S. Muto and T. Hamada, Platinum Metals of Technology, Sydney. He has an active interest in materials Rev., 1988, 32, (3), 110 science and engineering, particularly of the precious metals. 8 D. P. Dunne and C. M. Wayman, Metall. Trans. A, 1973, 4A, 147 Michael Witcomb is Professor and Director of the Electron Microscope Unit at the University of the Witwatersrand. His 9 S. Muto, R. Oshima and F. E. Fujita, Metall. Trans. A, research interests are in the microstructural characterisation of 1988, 19A, 2931 intermetallics, platinum alloys, hard metals and nanomaterials. 10 Y. Mishima, Y. Oya and T. Suzuki, Proc. Int. Conf. Martensitic Transformations (ICOMAT 86), 26–30 Lesley Cornish is Section Head of the Advanced Materials Group in the Physical Metallurgy Division at Mintek, as well as an Honorary Aug.‚ 1986, Nara, Japan, Japan Inst. of Metals, 1987, Professor at the University of the Witwatersrand. Her research pp. 1009–1014 interests include phase diagrams, platinum alloys and intermetallic 11 Y. Oya, U. Mishima and T. Suzuki, Z. Metallkd., compounds. 1987, 78, (H.7), 485 12 A. J. McAlister and D. J. Kahan, Bull. Alloy Phase Diagrams, 1986, 7, (1), 47 Searching at the European Patent Office 13 K. Otsuka and X. B. Ren, Intermetallics, 1999, 7, 511 To find an indication of the intellectual property and 14 P. G. Lindquist, “Structure and Transformation commercial activity within any area, for example, shape Behaviour of Ti-(Ni,Pd) and Ti-(Ni,Pt) Alloys”, Ph.D. Thesis, University of Illinois, U.S.A., 1988 memory alloys, the patents database, ‘esp@cenet’, of the 15 R. M. Waterstrat, Metall. Trans. A, 1973, 4A, 1585 European Patent Office: http://ep.espacenet.com/ is 16 R. M. Waterstrat, Metall. Trans. A, 1973, 4A, 455 useful. The database offers a free quick search facility. 17 “Binary Alloy Phase Diagrams”, ed. T. B. Massalski, In the “Worldwide” database, around 30 millions ASM, Materials Park, OH, 1986 18 JCPDS-ICDD, “Joint Committee for Powder past and present patent documents can be accessed, and Diffraction Standards – International Centre for can be searched with a combination of key words in the Diffraction Data”, ver. 2.16, Int. Center for Diff. “Title or Abstract” section. This allows further, more Data, Newtown Square, PA, 1995 19 Crystallographica, Oxford Cryosystems, version complex, searching. Using the terms: shape memory plat- 1.31, 3 Oct., 1997; www.oxfordcryosystems.co.uk inum, located 20 patents in October.

Platinum Metals Rev., 2003, 47, (4) 156 Automotive Exhaust Emissions Control

By Martyn V. Twigg Johnson Matthey Catalysts, Orchard Road, Royston, Hertfordshire SG8 5HE, U.K.

The technical sessions on emissions control at miles, and the even more demanding Partial Zero the Society of Automotive Engineers’ (SAE) 2003 Emissions Vehicle (PZEV) standards requiring SULEV World Congress, held in Detroit earlier this year emissions levels for 150,000 miles. These emis- were well attended and covered systems for con- sions are so low that measuring them (engineering ventional gasoline engines, lean-burn gasoline and targets ~ 0.008 g mile–1) requires state-of-the-art diesel engines (1). Sessions on emissions from analytical equipment. Such emissions can only be diesel engines attracted strong interest and more achieved by combining a highly efficient catalyst attendees than there were seats! This reflects the system with precise engine fuelling and efficient in- wide acceptance in Europe that modern diesel cars cylinder combustion. In fact, the catalytic have gained due to improvements in recent years. conversion of HC must take place within a few Driving characteristics of modern diesel cars are seconds of engine start-up, therefore mounting the now excellent with engine noise and smell virtual- three-way catalyst (TWC) close to the exhaust ly eliminated while high ‘bottom-end torque’ and manifold is essential. The use of TWCs (based on good fuel economy are maintained. This raises the metallic substrates with different cell densities) in possibility of using modern diesel engines in North this close-coupled position was described in a American ‘pick-up trucks’ and popular sport utility paper by Emitec, Johnson Matthey and South vehicles (SUVs) to achieve major fuel savings and West Research Institute (2003-01-0819). As reduced carbon dioxide (CO2) emissions. expected, higher cell density catalysts improved the However, there are major challenges in meeting light-off characteristics, but key are the engine ultra low emissions requirements for particulate start-up strategy and the rate of temperature matter (PM) and nitrogen oxides (NOx). increase provided by the hot exhaust gas. The In this article a selection of technical papers practical optimal catalyst cell density depends on highlighting the roles of platinum group metals the actual application. (pgms) in catalytic emissions control systems are The University of Stuttgart and Volkswagen reviewed. The reference numbers of the papers are (2003-01-1001) reported results from a mathemat- given in parentheses: most are available in SAE ical model of a TWC operating in a high Special Publications of selected papers (2). Two of conversion SULEV system based on the following these, dealing with diesel emissions, are available reactions: on a CD-ROM (‘Diesel Emission Measurement, H + 0.5O ® H O (i) Modeling, and Control’, SP-1754CD) (3). Here, 2 2 2 CO + 0.5O ® CO (ii) emissions control systems for conventional gaso- 2 2 C H + 4.5O ® 3CO + 3H O (iii) line engines are considered first, then lean-burn 3 6 2 2 2 C H + 5O ® 3CO + 4H O(iv) gasoline and lastly diesel engine technologies. 3 8 2 2 2 H2 + NO ® H2O + 0.5N2 (v) Conventional Gasoline Engine CO + NO ® CO2 + 0.5N2 (vi) Catalysts C3H6 + 9NO ® 3CO2 + 3H2O + 4.5N2 (vii) C H + 10NO ® 3CO + 4H O + 5N (viii) The most stringent car emissions requirements 3 8 2 2 2 Ce O + 0.5O ® 2CeO (ix) are the Californian Super Ultra Low Emissions Vehicle 2 3 2 2 (SULEV) standards that demand hydrocarbon The oxidation Reactions (i)–(iv), the reduction (HC) emissions over the American Federal Test Reactions (v)–(viii), and the catalyst’s uptake and Procedure (FTP) to be 0.01 g mile–1 after 120,000 release of oxygen Reaction (ix) describe the overall

Platinum Metals Rev., 2003, 47, (4), 157–162 157 chemistry taking place. A model in which the than newer cleaner engines), and on the initial rate mechanisms involved in oxygen storage and of exhaust gas temperature increase. release were combined in a single rate expression Nissan (2003-01-0816) described improve- gave an acceptable mathematical description when ments made in emissions from the first car tested against emissions from a SULEV car. The certified for PZEV credits. Engine-out emissions validating car had a rich start-up strategy with air had been reduced, and a more compact catalyst injected into the exhaust gas to ensure very rapid system was achieved by using ultra-thin-wall heating of the underfloor catalyst following a cold ceramic substrate (1.8 mil) of reduced thermal start. There was good agreement between mea- mass. Two CHTTM stages had also been incorpo- sured and simulated temperatures in the catalyst, rated, the first placed in the close-coupled and small differences were attributed to difficulties converter, behind the TWC, and the second in an of temperature measurement. There was also good underfloor position. The second CHTTM had a new agreement between simulated and measured cold- cerium-based oxygen storage component incorpo- start emissions. Special attention was given to rated into its TWC layer that improved aged HC transient behaviour and in general good agreement conversion. As a result catalyst volume was with the simulation was obtained. The model reduced from 3.9 to 1.8 litres, and the amount of helped in understanding the observed overall pgm was lowered while still maintaining the PZEV behaviour. requirements. The theme of advanced TWC formulations Hitachi (2003-01-0815) described eleven differ- requiring less pgms than current technologies – ent transition metal- and alkaline earth metal- developed at last year’s Congress (4) – was contin- exchanged zeolites for enhanced HC retention. ued by Honda (2003-01-0814). Honda described Silver-exchanged zeolite containing a few per cent TWCs containing perovskite and other mixed silver (Ag) was found to retain n-pentane to about metal oxides. Previously, perovskites lacked the 100ºC higher temperatures than pure zeolite. In stability for successful operation in modern TWCs, practice the low oxygen level in a car’s exhaust gas due, for example, to the formation of inactive alu- when operating around stoichiometry means the minates and silicates. Honda’s test vehicle was a released HC cannot be combusted, so an oxygen

2001 SULEV car with a 2.3 litre four cylinder storage component (CeO2) was incorporated into engine, a rapid warm-up strategy and a precisely the catalyst to aid combustion. Tests were made on controlled air/fuel ratio. The car had two under- a V6 engine that originally had a close-coupled floor catalysts: a 0.7 litre and a 1.0 litre on 600 cell TWC on each bank and also an underfloor TWC. inch–2 and 4.3 mil (1 mil = 0.001 inch) wall sub- The latter was replaced by the Ag-containing strates; the washcoat had 33 g ft–3 pgm containing CHTTM. Tail-pipe HC emissions were significantly platinum (Pt), palladium (Pd) and rhodium (Rh) improved, but the sensitivity of Ag catalysts to (4:25:4). After ageing to the equivalent of 120,000 thermal sintering and poisoning by, for example miles the car was still able to meet LEV-II LEV sulfur compounds, may seriously restrict actual standards for all three pollutants. use. Nevertheless, in the light of recent reports on the effectiveness of Ag-containing lean-NOx Catalysed Hydrocarbon Trap diesel catalysts (5), it is interesting to see Ag The use of a zeolite-based catalysed hydrocar- markedly influencing the performance of CHTs. bon trap (CHTTM) to control initially-formed HCs During driving, the on-board diagnostic (OBD) by retaining them until catalyst light-off is reached system measures oxygen storage capacity (OSC) of was discussed last year (4), and continued this year. a catalyst with two oxygen sensors, one upstream The effectiveness of such a system depends on the of it and one downstream. The catalyst selected for zeolite used to retain the HCs, and on factors such testing is usually the one nearest the engine as leg- as the types of HCs involved (older engines, for islative emissions requirements will not be met if instance, produce more unburned long-chain HCs this catalyst does not function correctly.

Platinum Metals Rev., 2003, 47, (4) 158 However, taking OSC measurements of very temperatures than used to reduce stored NOx. low emissions systems can be difficult. Volvo and The oxidation Reaction (x) is catalysed by Pt Emitec (2003-01-0818) reported an approach that which is also important for Reaction (xi) and for might help. They placed the first control oxygen the nitrate decomposition, Reaction (xii). sensor in the front catalyst, rather than in the open Rhodium is normally the catalyst for the NOx exhaust gas. This protects the sensor from the reduction Reaction (xiii), and Pd may be incorpo- effects of liquid water during cold starts, so the rated to help oxidise HCs that inhibit Reaction (x). early heating and functioning of the sensor are no Ford (2003-01-1162) described a rapid engine- longer concerns. based sulfation procedure in which sulfur dioxide

(SO2) is injected upstream of the NOx-trap. When NOx-Trapping Catalysts for compared with NOx-traps sulfated over an Lean-Burn Gasoline Engines extended period of normal use, the amount of sul- A lean-burn gasoline engine is not as fuel effi- fur absorbed was found to depend on total sulfur cient as a diesel engine, but they are being exposure, and both sulfated catalysts had similar developed because of their perceived advantages desulfation characteristics. Temperature is the over diesel engines. The emissions control systems most important factor once desulfation is thermo- being developed typically involve a TWC mounted dynamically allowed, and although the ratio of close to the exhaust manifold to control emissions SO2/H2S formed changes with richness, the desul- during stoichiometric start-up and high speed dri- fation rate follows a simple Arrhenius relationship. ving, and an underfloor NOx-trap to store NOx Ford (2003-01-1159) also examined NOx during lean operation when a TWC is ineffective release from NOx-traps during regeneration. The for NOx removal. The chemistry involved is main cause for the appearance of NOx is insuffi- shown in Reactions (x)–(xv). cient reductant, particularly under hot conditions. The regeneration process itself increases tempera- NO + 0.5O ® NO (x) 2 2 ture which destabilises the nitrate; the consump- NO + MCO ® MNO + CO (xi) 2 3 3 2 tion of reductant by other oxidised species exacer- MNO + H ® MO + NO + H O (xii) 3 2 2 bates this and increases temperature. In a joint 2NO + 2H ® N + 2H O (xiii) 2 2 2 contribution Ford and Mazda (2003-01-1160) MO + CO ® MCO (xiv) 2 3 examined these factors in more detail. They found MCO + SO ® MSO + CO (xv) 3 3 4 2 that increasing the amount of ceria-containing NOx is retained in the NOx-trap as a nitrate usu- mixed oxide in a NOx-trap increased the time for ally derived from an alkaline earth compound regeneration, as did the amount of NOx released (such as barium or strontium) or an alkali metal during this process. Although the presence of ceria compound (such as potassium), Reactions (x) and introduces additional OSC, it also facilitate hydro- (xi). Periodically the trap is exposed to short rich gen formation via the water gas shift reaction – so excursions to reduce stored NOx to nitrogen and there should be an optimum level of cerium. regenerate the trap, Reactions (xii) to (xiv). The DaimlerChrysler and OMG (2003-01-1161) basic materials are gradually converted to stable described the emissions control system for a new sulfates during prolonged use via reaction with sul- lean-burn supercharged direct injection engine fur trioxide (SO3) derived from sulfur compounds that has a close-coupled TWC and a dual flow sys- in the fuel, Reaction (xv). Thus the NOx-trap tem with a cooling section and a bypass to the capacity decreases over time, and rich regenerating underfloor NOx-trap. Active switching of gas pulses must be made more frequently. This has a between the main cooled section and the bypass detrimental effect on fuel economy. To recover enables the NOx-trap to operate in an optimal maximum NOx capacity the trap must be occa- temperature range over a wide range of vehicle sionally ‘desulfated’, essentially the reverse of running conditions. Moreover, restricting its expo- Reaction (xv), by treatment at higher reducing sure to high temperatures ensures long life for the

Platinum Metals Rev., 2003, 47, (4) 159 NOx-trap. A NOx sensor behind the NOx-trap is lower the combustion temperature, and including used to initiate and stop the regeneration process. devices to increase the gas temperature. Heating Emissions well below Stage IV levels were reported. devices have not been totally successful because the temperature rise from the exothermic PM Diesel Emissions Control combustion, if not controlled, can push the tem- Progress made in reducing diesel emissions last perature in the filter to above its melting point. year was reviewed by Corning (2003-01-0039) in One successful approach has been to combust what has become a traditional presentation by Tim the trapped PM with nitrogen dioxide (NO2). The Johnson. He indicated that tightening regulations combustion occurs at temperatures as low as over the next few years will force the introduction 250ºC, a temperature available during diesel truck of combined technologies for NOx and PM. or bus operation. The NO2 is obtained by oxidis- Diesel engines operate very lean, and when ing NO present in the exhaust gas over a Pt required, Pt-based oxidation catalysts achieve con- oxidation catalyst, Reaction (xix). The reaction is trol of CO and HC emissions according to inhibited by SO2, so low sulfur fuel is needed for Reactions (xvi) and (xvii). efficient operation. Under appropriate conditions such a device – an oxidation catalyst upstream of a CO + 0.5O ® CO (xvi) 2 2 particulate filter – can function continuously. This HC + O ® CO + H O (xvii) 2 2 2 is called a continuously regenerating trap (CRT â). Modern Pt catalysts for diesel cars have been for- For some heavy-duty applications NOx emis- mulated to cope with both the low-temperature sions can be reduced by applying exhaust gas operation resulting from the good fuel economy of recirculation (EGR) to the engine, while also con- diesel engines and, to some extent, with the effects trolling PM emissions and any additional PM of sulfur oxides derived from sulfur compounds in produced by EGR with a CRTâ system. Johnson the diesel fuel. The major future challenges are to Matthey and STT Emtec (2003-01-0048) reviewed reduce NOx emissions and PM (soot). the performance of over one thousand EGR-CRTâ systems installed on urban buses and other heavy- Catalytic Particulate Control Systems duty vehicles in Europe during the last four years. Diesel engine PM is aggregated carbon particles Typically the EGR-CRTâ system is as efficient as with a variety of adsorbed HCs and partially oxi- a CRTâ for HC, CO and PM reduction, and addi- dised organic compounds, together with water, tionally lowers NOx by 46–58%. and sulfuric and nitric acids. Controlling PM is Future legislation requires lower NOx emis- important due to their adverse health effects. sions, but a lower NOx/PM ratio will be less

Tremendous improvements have been made in favourable for the ‘CRT effect-with-NO2’ to oper- recent years to reduce the amount of PM pro- ate. One potential solution is to recycle NOx so it duced, but concern remains, particularly over is used several times to oxidise PM. Delft nanoparticles. Several kinds of filter can trap PM, University (2003-01-0379) described a Pt-catalysed but then the problem lies in removing the trapped ceramic foam filter in which the trapped PM is par-

PM – by oxidation to harmless CO2 and water – to tially removed by reaction with NO2. If this filter is prevent excess pressure drop building-up across placed upstream of a monolithic wall-flow filter, the filter. Diesel PM burns in air above about sufficient NO2 is available here to remove the 550ºC (Reaction (xviii)), a significantly higher tem- trapped PM. Delft only gave laboratory results. perature than that of normal diesel exhaust gas. One constraint may be pressure-drop limitations. Another potential solution is to use a catalysed PM + O ® CO + H O (xviii) 2 2 2 particulate filter with an upstream oxidation cata- NO + 0.5O ® NO (xix) 2 2 lyst, referred to as a CCRTTM (described by Several approaches have been used to remove Johnson Matthey (2002-01-0428) last year (4)). In the collected PM, such as using fuel additives to field trials on problematical applications the

Platinum Metals Rev., 2003, 47, (4) 160 CCRTTM could be regenerated better than a 200–250ºC for Pt, defined by the catalyst activity CRTâ, which in turn was much better than a catal- and the temperature at which complete HC oxida- ysed filter. Indeed, a CCRTTM can operate well in tion takes place. Formulations with copper work at situations where a CRTâ performance is marginal. higher temperatures (~ 350–400ºC); and there is This year Michigan Technological University current interest in Ag formulations (see above). (2003-01-0049) tested a low loaded (5 g ft–3 ) Pt- Iridium (Ir) has been used on a production lean- catalysed filter on a 1995 turbocharged 10.8 litre burn gasoline engine, and Industrial Power engine, and found good conversions for HCs, Alliance (2003-01-0044) examined its use on diesel aldehydes and CO, as well as some lean-NOx engines. under favourable conditions. The oxidation reac- In their paper, Industrial Power Alliance tions were less efficient than for a conventional reported that an Ir-based active lean-NOx catalyst oxidation catalyst; PM sulfate-derived emissions reduced NOx emissions on a Tier 1 (6 g kWh–1 ) were significantly increased because high sulfur- stationary heavy-duty diesel engine to Tier 3 levels content fuel was used. (4 g kWh–1 ), but the fuel economy penalty of 15% Corning and Donaldson (2003-01-0843) stud- was excessive. They improved fuel economy by ied pressure-drop variations of Pt-catalysed filters changing the fuel injection point and by operating loaded with PM, and highlighted the complexities. the catalyst in the optimum temperature range (by The way the filter is catalysed has a major impact masking its central portion). On applying EGR the on its PM loading characteristics. raw NOx was reduced and the lower oxygen con- While the conditions referred to above are typ- tent improved catalyst performance. However, at ical of heavy-duty, large, diesel engines, they are low NOx levels Ir catalysts appear inefficient, and less typical of small-engined cars where additional so this approach is unsuitable for more demanding ways to combust PM have to be considered. For standards where NOx-trapping and SCR systems instance, Ford (2003-01-0047) reported prelimi- are better suited. nary results for a 2.5 litre turbocharged engine Johnson Matthey (2003-01-0045) described the with a system having two active lean-NOx cata- optimisation of NOx-trapping catalysts for heavy- lysts (with fuel injection) followed by a duty diesel applications by choosing suitable Pt-catalysed filter (50 g ft–3 ). Ford used normal nitrate-forming phases to give improved high tem- diesel and ultra low sulfur fuel. The filter was perature performance. The low-temperature effective at removing PM; the less-than-one-per- NOx-trapping characteristics have also been cent PM that was not trapped had a size improved and so provide a wider operating tem- distribution similar to that of the raw gas. Filter perature window. The improvements include an regeneration was achieved by increasing the upstream Pt oxidation catalyst that removes HCs exhaust fuel injection rate and duration to give fil- and oxidises NO to NO2. ter temperatures high enough for PM combustion. The U.S. Environmental Protection Agency This worked well, with smooth regeneration (EPA) has a programme to define the capabilities taking place between 500–600ºC. During regener- of NOx-traps for heavy-duty applications. Their ation when using high sulfur fuel, high PM previous work has demonstrated that high NOx emissions occurred because the stored sulfate was conversions (> 90%) are possible with large cata- released, again highlighting the need for ultra low lyst volumes in a dual system with flow control sulfur diesel fuel. Information about the active valves to reduce the fuel needed to achieve rich lean-NOx performance was not provided. regenerating conditions (6). The EPA (2003-01- 0042) now reported an investigation of thermal Catalytic NOx Control Systems ageing in high temperature (510ºC) exhaust gas Moderate NOx conversions are possible – that is typical of high-load high-speed operation. using active lean-NOx catalysts – when HC reacts The actual catalyst temperature was higher during with NOx in the narrow temperature range, ~ reductive regeneration and, even when sulfur was

Platinum Metals Rev., 2003, 47, (4) 161 not present, the NOx conversion could signifi- were reported. As expected, the retention of PM cantly degrade over prolonged time. This effect and the conversions of HC and CO were also very depends on the catalyst formulation; the most high. A number of compact SCRTTM systems are in recent formulation examined suffered only slight service on vehicles, and their in-field performance deterioration. The work did not examine the will be reported later. impact of periodic high-temperature excursions for catalyst desulfation, and this will be the basis of Conclusions future work. Major advances are being made with pgm-based AVL (2003-01-0043) equipped two diesel cars catalytic exhaust emissions control systems, and with common rail fuelling and new control systems these are enabling stringent standards to be capable of providing rich exhaust-gas pulses via achieved. The overall efficiency of TWCs on gaso- post injections to regenerate a NOx-trap placed in line cars is now extremely high, and the amounts of front of a catalysed PM filter. The simultaneous pgm used to achieve ultra low standards are being reduction of about 90% PM and conversion of lowered as more advanced technologies are intro- more than 50% NOx was recorded, indicating the duced. In comparison, control of exhaust potential of this approach. However, a number of emissions from diesel engines is at a relatively early practical problems will require solving; for example stage of development, progress is rapid and more oil dilution resulting from frequent post injections exciting new results may be expected at the next could result in serious engine deterioration. Detroit SAE World Congress (7). Selective catalytic reduction (SCR) of NOx by ammonia (NH3) over a suitable catalyst can be an References efficient means to reduce NOx, for example see 1 Cobo Center, Detroit, Michigan, 3rd–6th March, Reaction (xx): 2003 2 ‘Advanced Catalysts for Emission Controls’, SP- 4NH3 + 4NO + O2 ® 4N2 + 6H2O (xx) 1756; ‘Emission Measurement and Testing 2003’, 2NH + NO + NO ® 2N + 3H O (xxi) SP-1757; ‘General Emissions’, SP-1758; ‘Lean 3 2 2 2 Engine NOx Control’, SP-1759; ‘Diesel Exhaust Emission Control’, SP-1754; ‘Diesel Emission In a joint presentation Johnson Matthey, Volvo Measurement and Modeling’, SP-1755. Papers in the Powertrain, Eminox and Robert Bosch (2003-01- last two publications are available on the CD-ROM 0778) described the design and performance of a SP-1754CD (‘Diesel Emission Measurement, Modeling, and Control’). The following contain system incorporating a SCR unit for NOx control related papers of interest: ‘In-Cylinder Diesel combined with a CRT â for PM control in an Particulate and NOx Control 2003’, SP-1738; extremely small package. The SCR catalyst is annu- ‘Homogeneous Charge Compression Ignition (HCCI) Combustion 2003’, SP-1742 â lar and placed around the CRT . The four-way 3 Copies of the CD-ROM and individual papers are emissions control system is designated a SCRTTM. available from: SAE, 400 Commonwealth Drive, The exhaust gas from the engine passes through Warrendale, PA 15096, U.S.A.; see www.sae.org the Pt oxidation catalyst of the CRTâ and PM fil- 4 M. V. Twigg, Platinum Metals Rev., 2003, 47, (1), 15 5 See for example: S. Satokawa, J. Shibata. K. Shimizu, ter; urea solution is then injected into the gas flow A. Satsuma and T. Hattori, Appl. Catal. B: Environ., before it passes through the annular SCR catalyst. 2003, 42, (2), 179 and references therein 6 SAE Technical Papers: 2001-01-1351; 2001-01- Residual NO2 not consumed in the PM combus- 3619; 2002-01-2871 tion promotes low-temperature SCR activity, 7 SAE 2004 World Congress, Cobo Center, Detroit, according to Reaction (xxi), and helps to provide Michigan, 8–11th March, 2004; see www.sae.org the excellent overall performance of the compact SCRTTM. The Author On a state-of-the-art 12 litre diesel engine with Martyn Twigg is the European Technology Director of Environmental Catalysts and Technologies, Johnson Matthey an NH3/NOx ratio of 0.95 (maximum possible Catalysts. His main interests are in applying advanced chemical NOx conversion is 95%), conversions of up to concepts to highly efficient emissions control systems. He is the author of numerous research papers in this area and is the editor 92% in the European Stationary Cycle test procedure of the book series “Fundamental and Applied Catalysis”.

Platinum Metals Rev., 2003, 47, (4) 162 Precious Metal Recovery from Spent Catalysts

By Piers Grumett Johnson Matthey Catalysts, Jeffreys Road, Enfield, Middlesex EN3 7PW, U.K.

A new process called AquaCat® for the recovery of precious metals from spent heterogeneous and homogeneous catalysts is described. The process has two stages, the first stage is to determine the precious metal content of a spent heterogeneous catalyst using new direct sampling technology. The second stage involves supercritical water oxidation, during which the carbonaceous material is converted into less noxious compounds, leaving the precious metals as their oxides.

Spent organic-based catalysts which contain This was followed by filtration and treatment via precious metals have traditionally been treated by the traditional incineration route. Figure 2 shows a incineration to recover the precious metal content. graph of the quantity of precious metals found by Incineration destroys the organic content of the direct sampling compared to incineration. Samples catalyst and leaves an ash which, before chemical are monitored against expectations for each batch. recovery is started, is sampled to determine the Computational fluid dynamics was used to precious metal content. However, a new more model the production-scale process. Output from environmentally-friendly process, AquaCat®, joint- the modelling is shown as a deviation from the ly developed and patented (1, 2) by Johnson average concentration in the vessel and is less than Matthey (3) and Chematur Engineering AB (4), 0.5% throughout most of the mixing vessel, see takes a different approach, see Figure 1.

Direct Sampling AquaCat® allows a spent heterogeneous cata- lyst, such as palladium or platinum on a carbon support, to have the metal content evaluated prior to treatment, directly from the as-received samples. The spent catalyst is received as a wet filter cake with a particle size distribution between 5 and 500 µm. This is added to water and surfactant in a ves- sel and mixed by agitation and by using a pumped recirculation loop in order to create a homoge- neous dispersion. A series of small representative samples of the mixture are then removed from the recirculation loop by automated extraction. These are collected together to form a sample which is sub-sampled in the laboratory and analysed for its precious metal content using standard analytical techniques. The sampling procedure was extensively vali- dated on a pilot scale before being scaled up for use in production. Over fifty samples of materials Fig. 1 Part of AquaCat® at the Enfield site. The direct representative of typical as-received spent catalyst sampling equipment is on the left. The feed tank and high were evaluated using the direct sampling process. pressure pump for the SCWO process are on the right

Platinum Metals Rev., 2003, 47, (4), 163–166 163 Figure 3. The concentration of material at the out- let and thus in the recirculation loop is equal to the average of the concentrations in the vessel. This ensures that the sample taken from the recircula- tion loop is representative.

Supercritical Water Oxidation The water-based slurry is then pumped into the feed tank for the next step in the process: super- critical water oxidation (SCWO). Water becomes supercritical at a temperature above 374ºC and pressure above 221 bar, when its viscosity is close to that of the gas phase but with higher density. In this process organic materials become soluble in the supercritical water, which is thus used as a sol- Fig. 2 Pilot scale validation graph of the amounts of vent for the oxidation. Inorganic materials, precious metal found by direct sampling compared with traditional incineration. Most points fall on or close to however, become insoluble. If feed materials con- line y = x, showing that the two evaluation procedures tain high levels of salts the SCWO process is not are equivalent. In fact they are statistically equivalent suitable. A flow diagram of the SCWO process is shown the site’s steam main). The product is cooled to in Figure 4. The SCWO process is based on ambient temperature and pressure prior to the Chematur Engineering’s supercritical water oxida- combustion gases being separated off. The pre- tion process, Aqua Critox®. Water is pressurised to cious metal oxides along with any other trace approximately 240 bar using a high-pressure elements, such as base metal oxides and silica, are pump, then heated to about 385°C to be in its sent on for further refining. supercritical phase. In the SCWO plant heteroge- neous (solid) catalysts are fed in a slurry form from the feed tank whereas homogeneous (liquid) cata- lysts are fed directly into the reactor.

Processing Heterogeneous Catalysts The slurry containing ~ 5% of spent catalyst is pumped up to a pressure of ~ 240 bar then passed through the economiser (heat-exchanger) into the heater to raise its temperature to 385ºC. The mate- rial then enters the reactor where sufficient high- pressure oxygen is injected to allow the heat of reaction to raise the temperature to ~ 600ºC. Next, quench water is injected to reduce the temperature before a second oxygen injection, which allows the reaction to go to completion. The organic compo- nents are converted to carbon dioxide, water and nitrogen and the metals form their oxides. The product from the reactor next passes Fig. 3 A computational fluid dynamics model of the through the economiser to preheat the incoming sampling vessel is presented. The output from the modelling is shown as the deviation from the average feed and then to a steam boiler (where up to one concentration in the vessel and it is less than 0.5% tonne per hour of steam is generated and fed into relative throughout most of the mixing vessel

Platinum Metals Rev., 2003, 47, (4) 164 Fig. 4 Flow diagram of the supercritical water oxidation process, based on Chematur Engineering’s supercritical water oxidation process, Aqua Critox®. Water is pressurised to ~ 240 bar using a high-pressure pump and then heated to ~ 385ºC so that it is in the supercritical phase. Heterogeneous (solid) catalysts are fed in a slurry form from the feed tank. In contrast, homogeneous (liquid) catalysts are fed directly into the reactor

Processing Homogeneous Catalysts • No SOx emissions because sulfur remains in Homogeneous catalysts are processed similarly the liquid effluent, and is treated off site as sulfate. to heterogeneous catalysts except that only high- • No dioxins or furans due to effective oxidation. pressure water is fed into the economiser. The The process is also more energy efficient as the homogeneous catalyst is injected directly into the energy from the exothermic reaction is used to reactor after the oxygen injection points because it preheat the incoming feed and generate steam. is not miscible with subcritical water and it often The process is continuous giving a greater degree contains phosphorus which would pyrolyse in the of control than in batch incineration. SCWO can preheating equipment when oxygen is not present. oxidise the organics in metal-organic composi- tions, particularly heterogeneous or homogen- The Benefits of AquaCat® eous precious metals catalysts, and produce metal Several environmental benefits result from oxides with few byproducts and low loss of pre- using the SCWO process instead of traditional cious metals. Catalysts containing higher levels of incineration. In part these are because the process residual organics can thus be treated more safely. is totally enclosed and so prevents the release of Benefits from direct sampling include the any harmful substances and metal loss. As such it acceptance of material in intermediate bulk con- achieves efficiencies for organic destruction close tainers, as well as drums, thus hazardous materials to 100%. Additional benefits include: are handled less. Incoming residues are check-

• Lower CO2 emissions – less fuel is required. weighed and sampled before any processing – • No CO emissions – the reaction goes to com- demonstrating confidence in the process efficacy. pletion. The prior sampling also gives earlier evaluation • No NOx emissions – lower reaction temperature. than in traditional processing.

Platinum Metals Rev., 2003, 47, (4) 165 References The Author 1 S. Collard, A. Gidner, B. Harrison and L. Stenmark, Piers Grumett is the Production Manager for Aquacat®, Johnson World Appl. 01/83,834 Matthey Catalysts, at the Enfield site, U.K. He has managed 2 Filtration & Separation, June 2003, 40, (5) , 16 and ref- Aquacat® from its initial stages, through installation, to current day- erences therein to-day operations. His interests include continuous improvement 3 http://www.chemicals.matthey.com/ of process operations and implementing operational changes. 4 http://www.chematur.se/ Other interests are environmentally-friendly procedures and safety. Hydrogen Economy Forum in Russia

SECOND INTERNATIONAL SYMPOSIUM ON SAFETY AND ECONOMY OF HYDROGEN TRANSPORT IFSSEHT-2003 was held from 18th to 22nd August State Physics, Chernogolovka) who looked at the phase at Sarov, Russia, where about 250 delegates from 12 equilibria at high pressures. countries attended a range of presentations on various The influence of H and vacancies on the evolution of aspects of hydrogen (H). The symposium also commem- structure in thermodynamically open Pd-based alloys orated the 60th anniversary of pioneering H utilisation was discussed by A. A. Katsnelson, V. M. Avdyukhina, by Boris Shelishch who, during the Siege of Leningrad, A. A. Anishchenko and G. P. Revkevich (Moscow State devised H-powered vehicles. Selected papers, some relat- University). B. A. Spiridonov and V. N. Ermilin ing to the platinum metals, are reported here. (Voronezh State Technical University, Russia) described Papers looked at atomic H energy, nuclear ways to chemical deposition of a catalytic Pd layer for a H sen- produce H from water, the H economy, and the Kyoto sor. Generation of a colloidal layer of Pd was involved. agreement effects on Russia. Safe ways to process H Mechanical instability in concentrated non-homoge- from the H2S trapped in the Black Sea were described by neous M-H media, M = Pd, Nb, V, was examined by L. V. G. Kashiya (Sukhumi Physical-Technical Institute, V. Spivak and N. E. Skryabina (Perm State University, Tbilisi, Georgia). More traditional H production using Russia). Equilibrium deuterium pressure over Pd and its electrolysers in fuelling stations for various projects in alloys was described by S. V. Dyomina, M. V. Glagolev Europe (ECTOS, CUTE and CEP) was examined by A. and A. I. Vedeneev (Russian Federal Nuclear Centre, Cloumann and K. Sollid (Norsk Hydro Electrolysers, Sarov). An analysis of stationary isotherms of H perme- Norway). Modules to extract pure H from industrial gas ability in Pd alloy membranes was described by L. L. mixtures, using palladium (Pd) alloy (Pd-In-Ru, Pd-Cu Murav’yov, A. B. Vandyshev and M. Sh. Gadel’shin and Pd-Y) thin foil membranes, diameter 50–150 mm, (Institute of Engineering Science, Ekaterinburg, Russia). were evaluated by D. I. Slovetsky, E. M. Chistov and N. A. L. Gusev (Russian Federal Nuclear Centre, Sarov) R. Roshan (A. V. Topchiev Institute, Moscow). described research underway on low-temperature H Micro- and nano-patterning of silicon (Si) wafer sub- detectors and absorbers, including one based on pal- strates by sputtering Pd and platinum (Pt) for H ladised manganese (Mn) dioxide with a protective anti- separation membranes in reformers for fuel cells were oxidant membrane of thin-walled quartz shells. He fur- discussed by H. Presting and colleagues from Daimler- ther described work with Voronezh State University into Chrysler, Germany, and the Institute of Microelectronics the effect of H on the electrical properties of metal oxide Technology, Chernogolovka, Russia. films alloyed with Si. Lastly, work with the Institute of Work on H in metals and alloys began with a survey Problems of Chemical Physics, Chernogolovka, on the of H diffusion coefficients in Pt, Pd and their alloys, pre- production of palladised films of Mn and Co oxides, sented by J. Cv ermák (Institute of Physics, Prague) and F. which can serve as the basis of H sensors, was mentioned. A. Lewis (Queen’s University, Belfast). Problems with Abstracts of the proceedings have been published in residual stress in hollow cylinders related to diffusion English and Russian as an International Scientific Journal for problems were described by N. M. Vlasov and I. I. Fedik Alternative Energy and Ecology (ISJAEE) Special Issue, (“Louch” Research Institute, Russia), while the role of ISSN 1608-8298, http://isjaee.hydrogen.ru/, available segregation at dislocations and grain boundaries in Pd from the Scientific Technical Centre “TATA”, PO Box and some other metals was discussed by Yu. S. Nechaev 787, Sarov, Nizhni Novgorod Region, 607183 Russia; and G. V. Filippov (Bardin Central Research Institute of Fax: +7 (83130) 63107; E-mail: [email protected]. Ferrous Metallurgy, Moscow). F. A. LEWIS Stable and unstable equilibria in metal-H systems, Fred Lewis is retired from Queen’s University, Belfast, after many such as rhodium-H, were examined by V. E. Antonov, I. years of research into hydrogen diffusion in palladium and O. Bashkin and E. G. Ponyatovsky (Institute of Solid- palladium alloys. These are still his main interests.

Platinum Metals Rev., 2003, 47, (4) 166 The Discoverers of the Iridium Isotopes

THE THIRTY-SIX KNOWN IRIDIUM ISOTOPES FOUND BETWEEN 1934 AND 2001

By J. W. Arblaster Coleshill Laboratories, Gorsey Lane, Coleshill, West Midlands B46 1JU, U.K.

This paper is the second in a series of reviews of work performed that led up to the discoveries of the isotopes of the six platinum group elements. The first review, on platinum isotopes, was published in this Journal in October 2000 (1). Here, a brief history of the discovery of the thirty-six known isotopes of iridium in the sixty-seven years from the first discovery in 1934 to 2001 is considered in terms of the discoverers.

Of the thirty-six isotopes of iridium known Laboratory, University of Rome, identified a 20 today, only two occur naturally with the following hour activity (activity is generally used to indicate authorised isotopic abundances (2): the half-life of a non-specified isotope) after bom- barding iridium with slow neutrons (9). In 1935, the same group (10) refined the half- The Naturally Occurring Isotopes of Iridium life to 19 hours, although Sosnowski (11) was Mass number Isotopic abundance, % unable to confirm this period but instead obtained activities of 50 minutes and three days for the half- 191 Ir 37.3 lifes. In 1936, Amaldi and Fermi (12) also discov- 193 Ir 62.7 ered an activity which they assigned to iridium, but its half-life was 60 days. In the same year Cork and Although Arthur J. Dempster (3) is credited Lawrence (13) bombarded platinum with with the discovery of these two isotopes at the deuterons (deuterium ions) and obtained activities University of Chicago, Illinois, in late 1935, using a with half-lifes of 28 minutes and 8.5 hours which new type of mass spectrograph that he had devel- they claimed were definitely associated with iridi- oped; earlier that year Venkatesachar and Sibaiya um following chemical identification. In 1937 (4) of the Department of Physics, Central College, Pool, Cork and Thornton (14) bombarded iridium Bangalore, India, had observed isotopic shifts in with neutrons and obtained a 15 hour activity the hyperfine arc spectrum of iridium which they which was very similar to that obtained by Fermi suggested were due to masses 191 and 193 in the and colleagues back in 1934. approximate ratio of 1:2. At that time, this seemed However, although in 1935 Dempster (3) had to be incorrect as it resulted in an atomic weight identified the naturally occurring isotopes, and the for iridium of 192.4 which was much lower than various radioactive discoveries could probably be the then accepted value of 193.1 (5). However, in assigned to the missing 192Ir, 194Ir or 195Ir, Livingston 1936, Sampson and Bleakney (6) carried out a pre- and Bethe (15), in a review in 1937, concluded that cision determination of the isotopic ratio using a the situation was confused and that no firm mass mass spectrograph. This confirmed the above assignments could be given at that time. However, approximate ratio and eventually, in 1953, the in the same year McMillan, Kamen and Ruben of atomic weight was lowered to 192.2 (7). the Department of Physics and Chemistry at the University of California (16) confirmed the 19 Artificial Iridium Isotopes hour activity of Fermi and colleagues (9, 10) and Almost immediately after the published discov- correctly assigned it to 194Ir while they also con- ery of artificial radioactivity by Curie and Joliot in firmed the 60 day activity of Amaldi and Fermi 1934 (8), Fermi and colleagues of the Physics (12) which they assigned to 192Ir. Actually

Platinum Metals Rev., 2003, 47, (4), 167–174 167 Enrico Fermi 1901–1954 The physicist Enrico Fermi was born in Rome, Italy. In 1926 Fermi discovered the statistical laws governing the behaviour of particles of quantum spin one half, which are now known as fermions. A year later he became Professor of Theoretical Physics at the University of Rome where he evolved the theory of beta decay. In 1934 he set up the group which led to the discovery of numerous artificial radioactive isotopes obtained by bombarding elements with neutrons and for this he received the 1938 Nobel Prize in Physics. Immediately afterwards he moved to the United States, first to Columbia University, then to the University of Chicago to be Professor of Nuclear Studies. He was a leading member of the team that produced, on 2nd December 1942, the first controlled nuclear chain reaction. After the war he concentrated on high energy physics and cosmic rays. Element 100 is named fermium in his honour University of Chicago, courtesy of AIP Emilio Segrè Visual Archives

Philip John Woods Professor of Nuclear Physics at the University of Edinburgh. Philip Woods is a spokesman of a British- American collaboration that has performed experiments at the Argonne National Laboratory, Chicago, resulting in the discovery and measurement of a large number of proton-emitting isotopes. These include the four most unstable iridium isotopes from 164Ir to 167Ir. The object to the right of Philip Woods is the pioneering double- sided silicon strip detector (DSSD) used to identify iridium isotopes by their radioactive decays

Platinum Metals Rev., 2003, 47, (4) 168 The Discoverers of the Iridium Isotopes

Mass number Half-life Decay modes Year of Discoverers Ref. Notes discovery*

164m 100 ms p 2000 1: Kettunen et al. 22 A 2: Mahmud et al. 23 165m 300 msp, a 1995 Davids et al. 20, 21 166 10.5 ms a, p 1995 Davids et al. 20, 21 166m 15.1 ms a, p 1981 Hofmann et al. 25 B 167 35.2 ms a, p, EC + b+ 1995 Davids et al. 20, 21 167m 30.0 ms a, EC + b+?, p 1981 Hofmann et al. 25 C 168 125 ms a?, EC + b+? 1978 Cabot et al. 27 D 168m 161 ms a 1995 Page et al. 26 169 780 ms a, EC + b+? 1999 Poli et al. 28 E 169m 310 ms a, EC + b+ 1978 1: Cabot et al. 27 F 2: Schrewe et al. 29 170 870 ms EC + b+, a 1995 Page et al. 26 G 170m 440 ms EC + b+, IT, a 1977 1: Cabot et al. 31 H 2: Schrewe et al. 29 171 3.2 s a, EC + b+, p? 2001 Rowe et al. 32 171m 1.40 s a, EC + b+, p? 1966 Siivola 19 I 172 4.4 s EC + b+, a 1991 Schmidt-Ott et al. 34, 35 172m 2.0 s EC + b+, a 1966 Siivola 19 J 173 9.0 s EC + b+, a 1991 1: Bouldjedri et al. 36 2: Schmidt-Ott et al. 34, 35 173m 2.20 s EC + b+, a 1966 Siivola 19 K 174 9 s EC + b+, a 1991 1: Bouldjedri et al. 36 2. Schmidt-Ott et al. 34, 35 174m 4.9 s EC + b+, a 1966 Siivola 19 L 175 9 s EC + b+, a 1966 Siivola 19 176 8 s EC + b+, a 1966 Siivola 19 177 30 s EC + b+, a 1966 Siivola 19 178 12 s EC + b+ 1970 Akhmadzhanov et al. 37, 38 179 1.32 min EC + b+ 1971 Nadzhakov et al. 39 M 180 1.5 min EC + b+ 1970 1: Akhmadzhanov et al. 37, 38 2: Nadzhakov et al. 39 181 4.90 min EC + b+ 1970 1: Akhmadzhanov et al. 37, 38 2: Nadzhakov et al. 39 182 15 min EC + b+ 1961 Diamond et al. 40 183 58 min EC + b+ 1960 1: Lavrukhina, Malysheva 41 and Khotin 2: Diamond et al. 40 184 3.09 h EC + b+ 1960 1: Baranov et al. 42 2: Diamond et al. 40 185 14.4 h EC + b+ 1958 Diamond and Hollander 43 186 16.64 h EC + b+ 1957 Scharff-Goldhaber et al. 44 N 186m 1.92 h EC + b+, IT? 1962 Bonch-Osmolovskaya et al. 46 187 10.5 h EC + b+ 1958 Diamond and Hollander 43 187m 30.03 ms IT 1962 Ramaev, Gritsyna and Korda 47 188 41.5 h EC + b+ 1950 Chu 48 188m 4.2 ms IT, EC + b+ 1970 Goncharov et al. 49 189 13.2 d EC 1955 Smith and Hollander 45 189m1 13.3 ms IT 1962 Ramaev, Gritsyna and Korda 47 189m2 3.7 ms IT 1974 1: André et al. 50 2: Kemnitz et al. 51

* The year of discovery is taken as available manuscript and conference dates. Where these are not available then the year of discovery is the publishing date

Platinum Metals Rev., 2003, 47, (4) 169 The Discoverers of the Iridium Isotopes (cont.)

Mass number Half-life Decay modes Year of Discoverers Ref. Notes discovery*

190 11.78 d EC + b+ 1946 Goodman and Pool 52 190m1 1.120 h IT 1964 Harmatz and Handley 53 190m2 3.087 h EC + b+, IT 1950 Chu 48 191 Stable – 1935 Dempster 3 191m 4.94 s IT 1954 1: Butement and Poë 54 2: Mihelich, McKeown 55 and Goldhaber 3: Naumann and Gerhart 56 192 78.831 d b–, EC 1937 McMillan, Kamen and Ruben 16 O 192m1 1.45 min IT, b– 1947 Goldhaber, Muehlhouse 57 P and Turkel 192m2 241 y IT 1959 Scharff-Goldhaber and McKeown 58 Q 193 Stable – 1935 Dempster 3 193m 10.53 d IT 1956 Boehm and Marmier 60 194 19.28 h b– 1937 McMillan, Kamen and Ruben 16 R 194m1 31.85 ms IT 1959 Campbell and Fettweiss 61 194m2 171 d b– 1968 Sunjar, Scharff-Goldhaber 62 S and McKeown 195 2.5 h b– 1952 Christian, Mitchell and Martin 65 195m 3.8 h b–, IT 1967 Hofstetter and Daly 66 196 52 s b– 1966 Venach, Münzer and Hille 67 T 196m 1.40 h b–, IT? 1966 Jansen and Pauw 69 U 197 5.8 min b– 1952 Christian, Mitchell and Martin 65 V 197m 8.9 min b–, IT? 1976 Petry et al. 72, 73 W 198 8 s b– 1972 Schweden and Kaffrell 74 X 199 (20 s) b– 1992 Zhao et al. 76 Y

Notes to the Table

A 164 m Ir Mahmud et al. (23) considered that the nuclide observed was an isomeric state not the +62 ground state. The half-life is a weighted average of 113 –30 µs determined by Kettunen et +46 al. (22) and 58 –18 µs determined by Mahmud et al. (23). B 166 m Ir Only the alpha energy was measured. The half-life was determined by Page et al. in 1995 (26) while the isomeric state assignment was by Davids et al. (21). C 167 m Ir Only the alpha energy was measured. The half-life was determined by Page et al. in 1995 (26) while the isomeric state assignment was by Davids et al. (21). D 168 Ir Only the alpha energy was measured. The half-life was determined by Page et al. in 1995 (26). 169 +462 E Ir The half-life was normalised from 638 –237 ms determined by Poli et al. in 1999 (28). F 169 m Ir The isomeric state assignment was by Poli et al. (28). The half-life is a weighted average of +90 308 ± 22 ms determined by Page et al. (26) and 323 –60 ms by Poli et al. (28). G 170 Ir The half-life was selected by Baglin (30). H 170 m Ir The isomeric state assignment was by Page et al. (26). The half-life was selected by Baglin (30). I 171 m Ir The half-life was selected by Baglin (33) who also assigned the activity to be an isomeric state. J 172 m Ir The isomeric state assignment was by Schmidt-Ott et al. (34).

* The year of discovery is taken as available manuscript and conference dates. Where these are not available then the year of discovery is the publishing date

Platinum Metals Rev., 2003, 47, (4) 170 Notes to the Table (cont.)

K 173 m Ir The isomeric state assignment was by Schmidt-Ott et al. (34). L 174 m Ir The isomeric state assignment was by Schmidt-Ott et al. (34). M 179 Ir Half-lifes determined by Nadzhakov et al. (39) appear to be systematically in error but the discovery is otherwise accepted. N 186 Ir The isotope was actually discovered by Smith and Hollander in 1955 (45) but was wrongly assigned to 187 Ir. O 192 Ir The isotope was first observed as a non-specific activity by Amaldi and Fermi in 1936 (12). P 192 m1 Ir The isotope was actually discovered by McMillan, Kamen and Ruben in 1937 (16) but was wrongly assigned to 194 Ir. Q 192 m2 Ir Scharff-Goldhaber and McKeown only determined the half-life to be greater than five years. The accepted value was determined by Harbottle in 1969 (59). R 194 Ir The isotope was first observed as a non-specific activity by Fermi et al. in 1934 (9) and Amaldi et al. in 1935 (10). S 194 m2 Ir A 47 s activity described as being an isomer of 194 Ir by Hennies and Flammersfeld in 1959 (63) could not be found by Scharff-Goldhaber and McKeown (64). T 196 Ir The isotope was first observed by Butement and Poë in 1953 (68) but was wrongly assigned to 198 Ir. U 196 m Ir Jansen and Pauw (69) suggested that the 20 h activity originally assigned to 196 m Ir by Bishop in 1964 (70) was actually a mixture of 196 m Ir and 195 Ir. V 197 Ir The 5.8 min half-life isotope was assigned to the ground state by Petry et al. in 1978 (71). W 197 m Ir The 8.9 min half-life isotope was assigned to be the isomeric state by Petry et al. in 1978 (71). X 198 Ir Details of this isotope were first given in the open literature by Szaley and Uray in 1973 (75). Y 199 Ir Only the mass of the isotope was determined. The half-life and decay mode were estimated from nuclear systematics (24).

Decay Modes a Alpha decay is the emittance of alpha particles which are 4He nuclei. Thus the atomic number of the daughter nuclide is lower by two and the mass number is lower by four. b– Beta or electron decay for neutron-rich nuclides is the emittance of an electron (and an anti-neutrino) as a neutron decays to a proton. The mass number of the daughter nucleus remains the same but the atomic number increases by one. b+ Beta or positron decay for neutron-deficient nuclides is the emittance of a positron (and a neutrino) as a proton decays to a neutron. The mass number of the daughter nucleus remains the same but the atomic number decreases by one. However, this decay mode cannot occur unless the decay energy exceeds 1.022 MeV (twice the electron mass in energy units). Positron decay is always associated with orbital electron capture (EC). EC Orbital electron capture. The nucleus captures an extranuclear (orbital) electron which reacts with a proton to form a neutron and a neutrino, so that, as with positron decay, the mass number of the daughter nucleus remains the same but the atomic number decreases by one. IT Isomeric transition, in which a high energy state of a nuclide (isomeric state or isomer) usually decays by cascade emission of g (gamma) rays (the highest energy form of electromagnetic radiation) to lower energy levels until the ground state is reached. However, certain low level states may also decay independently to other nuclides. p The emittance of protons by highly neutron-deficient nuclides. As the neutron:proton ratio decreases a point is reached where there is insufficient binding energy for the last proton which is therefore unbound and is emitted. The point at which this occurs is known as the proton drip line and such nuclides are said to be “particle unstable”.

Platinum Metals Rev., 2003, 47, (4) 171 Appendix Some of the Terms Used for this Review Atomic number the number of protons in the nucleus Mass number the combined number of protons and neutrons in the nucleus Nuclide and isotope A nuclide is an entity characterised by the number of protons and neutrons in the nucleus. For nuclides of the same element the number of protons remains the same but the number of neutrons may vary. Such nuclides are known collectively as the isotopes of the element. Although the term isotope implies plurality it is sometimes used loosely in place of nuclide. Half-life the time taken for the activity of a radioactive nuclide to fall to half its previous value Electron volt (eV) The energy acquired by any charged particle carrying a unit (electronic) charge when it falls through a potential of one volt, equivalent to 1.602 × 10–19 J. The more useful unit is the mega (million) electron volt, MeV.

McMillan, Kamen and Ruben assigned the original In the Table of the Discoverers of the Iridium identification of the 60 day activity to Fomin and Isotopes the date of discovery is a manuscript or Houtermans in 1936 (17), but these two appeared conference date, or, if unavailable, then a publish- not to have produced this activity but simply men- ing date. The half-lifes are mainly those selected in tioned its discovery by Amaldi and Fermi. the NUBASE database (24) with new or revised However Fomin and Houtermans became credited values being referenced in the Notes to the Table. with the first observation and this confusion was not resolved until 1951 (18). None of the other Acknowledgement activities reported prior to 1938 have proved to be Thanks to Mrs Linda Porter for typing the manu- correct. script. As with platinum, the most prolific decade for the discovery of iridium isotopes was the 1960s with References Antti Siivola, who was then at the Lawrence 1 J. W. Arblaster, Platinum Metals Rev., 2000, 44, (4), 173 2. K. J. R. Rosman and P. D. P. Taylor, Commission Radiation Laboratory, Berkeley, California, produc- on Atomic Weights and Isotopic Abundances, ing and identifying seven new isotopes in 1966 (19). Subcommittee for Isotopic Abundance Measurements, More recently there has been a concentration on the Pure Appl. Chem., 1998, 70, (1), 217 3 A. J. Dempster, Nature, 1935, 136, 909 proton-rich isotopes, and in 1995 a British- 4 B. Venkatesachar and L. Sibaiya, Nature, 1935, 136, American team, one of the leading members of 37 which was Philip J. Woods, announced the produc- 5 G. P. Baxter, O. Hönigschmid, P. Lebeau and R. J. tion of the three proton-emitting isotopes 165Ir, 166Ir Meyer, J. Am. Chem. Soc., 1935, 57, 787 and 167Ir and this research group was therefore the 6 M. B. Sampson and W. Bleakney, Phys. Rev., 1936, 50, 732. first to cross the proton drip line in iridium (20, 21). 7 E. Wichers, J. Am. Chem. Soc., 1954, 76, 2033 More recently two groups have independently dis- 8 I. Curie and F. Joliot, Comptes Rendu, 1934, 198, 254 covered the even lighter proton-emitting isotope 9 E. Fermi, E. Amaldi, O. D’Agostino, F. Rasetti and 164Ir, the first at the Department of Physics, E. Segrè, Proc. R. Soc. Lond., 1934, A146, 483 10 E. Amaldi, O. D’Agostino, E. Fermi, B. Pontecorvo, University of Jyväskylä, Finland (22), and the second F. Rasetti and E Segrè, Proc. R. Soc. Lond., 1935, by the British-American team mentioned above (23). A149, 522 The discovery of four particle-unstable isotopes (i.e. 11 L. Sosnowski, Comptes Rendu, 1935, 200, 922 proton emitters) for one element is a record. 12 E. Amaldi and E. Fermi, Ric. Sci. Riv., 1936, 7, (1), 56 Because the half-life of 164Ir is likely to be less than 13 J. M. Cork and E. O. Lawrence, Phys. Rev., 1936, 49, 788 100 ms it is likely that there may be extreme difficul- 14 M. L. Pool, J. M. Cork and R. L. Thornton, Phys. ty in producing and identifying even lighter isotopes. Rev., 1937, 52, 239

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Osmium tetroxide, OsO4, is an efficient oxidation cooxidant, with (DHQD)2PHAL ligand added to PEM- catalyst, well known for olefin hydroxylation and dihy- MC OsO4 catalyst; acetone is then removed. Addition of droxylation reactions. For the catalytic asymmetric dihy- a non-ionic surfactant, Triton® X-405 (octylphenoxy- droxylation (AD) of olefins, addition of a chiral ligand, polyethoxyethanol) was found to increase yield and ee such as (DHQD)2PHAL, to the OsO4 reaction mixture, and reduce Os leaching. Issues around catalyst solubility gives access to a wide range of enantiomerically pure were resolved by adding the ligand directly to the reac- vicinal diols. The chiral ligand is based on a biscinchona tion mixture. Product diols were obtained in better yield alkaloid with a phthalazine core (1). without catalyst deactivation even after three runs. Os

However, OsO4 is highly toxic and volatile and diffi- leaching was completely suppressed by neutralising with cult to use, and to avoid hazards OsO4 has sometimes aqueous H2SO4. Other olefins behave similarly and the been bound to polymers. Replacing organic solvents by PEM-MC OsO4 can be separated by filtration, recovered water for chemical reactions is an additional interest. and reused without loss of activity. Now, a team from The University of Tokyo, Japan, References have developed a microencapsulated OsO system, 4 1 K. B. Sharpless, W. Amberg, Y. L. Bennani, G. A. Crispino, based on poly(phenoxyethoxymethylstyrene-co-styrene) J. Hartung, K.-S. Jeong, H.-L. Kwong, K. Morikawa, Z.-M. (PEM-MC OsO ) (2) which can perform AD of olefins Wang, D. Xu and X.-L. Zhang, J. Org. Chem., 1992, 57, (10), 4 2768 with water as the sole solvent without catalyst leaching. 2 T. Ishida, R. Akiyama and S. Kobayashi, Adv. Synth. Catal., The system uses a H2O-acetone solvent and K3Fe(CN)6 2003, 345, (5), 576 and references therein

Platinum Metals Rev., 2003, 47, (4) 174 Bicentenary of Four Platinum Group Metals

PART I: RHODIUM AND PALLADIUM – EVENTS SURROUNDING THEIR DISCOVERIES

By W. P. Griffith Department of Chemistry, Imperial College, London SW7 2AZ

The years 2002 to 2004 mark the bicentenaries of the discoveries of rhodium, palladium, iridium and osmium. Two remarkable people were responsible for their discoveries – William Hyde Wollaston (1766–1828) the discoverer of rhodium and palladium, and his friend Smithson Tennant (1761–1815) the discoverer of iridium and osmium. This and a subsequent paper will seek to retell the stories of their discoveries, and to indicate the growing usefulness of the metals throughout the nineteenth century to their importance today. In this first part we will discuss Wollaston and his discoveries. Part II, to be published in a later issue, will complete the story with Tennant’s discoveries of the more intractable elements iridium and osmium.

In 1789, Lavoisier defined the element as: described it in an anonymous handbill in April 1803. Later that year Wollaston, still anonymously, du dernier terme auquel parvient l’analyse published the information in Nicholson’s Journal (5). (the last point that analysis can reach). He listed In November 1803 he confided its discovery to his thirty-three ‘simple substances’, of which we friend, Sir Joseph Banks, the President of the would now recognise twenty-three as elements. Royal Society (6, 7). Eventually he commented on Ten of these had been known since antiquity and it in the Philosophical Transactions of the Royal Society in seventeen more were discovered before 1789, but 1804 (8) and finally published it openly in 1805 (9), the golden age of discovery and isolation of the so the year 2003 is thus reasonable to claim for the elements followed after Lavoisier’s definition. bicentenary of its publication if not for its discov- Fourteen years later, the first four of what we now ery. know as the six platinum group metals (pgms) In 1804, Wollaston published a paper on the were discovered in England: rhodium and palladi- discovery of rhodium (8), but it is likely that pre- um by Wollaston, and iridium and osmium by his liminary work had occurred in the previous year. close friend and collaborator, Smithson Tennant. By contrast, iridium and osmium pose few prob- By the end of the nineteenth century, forty-seven lems as Smithson Tennant announced their more elements were known (the remaining ele- discovery in 1804 (10). ments and some synthetic elements (1) were discovered in the twentieth century). While plat- William Hyde Wollaston FRS inum had been known about in the fifteenth In this Journal in 1966, the bicentenary of the century and perhaps even earlier (2), the last of the birth of Wollaston was commemorated (11). six pgms, ruthenium, was not discovered until However, although Wollaston was a remarkable 1844 by Karl Karlovich Klaus (1796–1864) (3). man and an important figure in many branches of science, as yet no full-scale biography of him has Platinum Group Metal Chronology been published. Curiously, the perhaps rather less It is something of a simplification to claim the eminent Smithson Tennant has fared better in this years 2003 and 2004 as the bicentenaries of the dis- respect. This summary is drawn from a number of coveries of palladium and rhodium, respectively. accounts of Wollaston’s life (2, 4, 6, 11, 12, 13). There is evidence from Wollaston’s notebooks Wollaston was born in East Dereham, Norfolk, that he had discovered palladium (which he first on 6th August 1766, and educated at Charterhouse called Ceresium) as early as 1802 (2, 4). He first School, London. He went to Caius College,

Platinum Metals Rev., 2003, 47, (4), 175–183 175 William Hyde Wollaston FRS 1766–1828 Discoverer of palladium and rhodium, and the first to produce malleable platinum. Born in Norfolk, Wollaston lived most of his adult life in London. In 1793 he obtained a doctorate in medicine from Cambridge University. While practicing medicine, he became interested in metallurgy, chemistry, physics and crystallography which from 1800 onward occupied him fully. Wollaston also invented various optical instruments. He was the first to observe (but uncomprehendingly) the dark lines in the solar spectrum.....he demonstrated the identity of frictional and voltaic electricity....he made important contributions to the design of voltaic batteries (6). The scale and variety of his research made him one of the most influential scientists of his time From a portrait by John Jackson, by courtesy of The Royal Society

Cambridge in 1782, and at this time his very pro- duction of malleable platinum, in the isolation of ductive friendship with Smithson Tennant began, the four metals which concern us here, and in as did their joint experiments on platinum concen- some organic chemistry. On Christmas Eve in trates. In 1787 he was elected a Senior Fellow of 1800 they bought 5959 Troy ounces of alluvial Caius College and held this position until his death platinum ore containing some 80 per cent of plat- on 22nd December 1828. In 1789 he became a inum, from Nueva Granada (now Colombia), physician in Huntingdon, and two years later he set South America, which had been smuggled into the up a practice in London at 18 Cecil Street (now Ivy country via Kingston, Jamaica, at the then consid- Bridge Lane), off the Strand. In 1793 he was erable cost of £795. During their experiments on awarded an M.D., and on 6th March 1794 he was the preparation of malleable platinum Wollaston elected a Fellow of The Royal Society. Those noted that preliminary treatment of the crude ore proposing him included Henry Cavendish and Sir with aqua regia dissolved most of the material, but William Herschel. small quantities of a black, insoluble component In 1797, Wollaston entered into a partnership remained. Wollaston investigated the soluble part, with Smithson Tennant. Tennant had substantial which he was later to show contained rhodium and private means, and they collaborated in the pro- palladium in addition to platinum, while Tennant

Platinum Metals Rev., 2003, 47, (4) 176 examined the insoluble portion, which contained rate measurements of the positions of crystal faces iridium and osmium. in minerals. This and his other contributions to In 1800 Wollaston retired from medicine, per- mineralogy are commemorated, not only in the haps because he failed to obtain a position at St. inosilicate minerals wollastonite CaSiO3 (named in George’s Hospital. In 1801 he bought a house at his honour by F. Léman in 1818) and another 14 Buckingham Street (now Greenwell Street) and form of it, pseudowollastonite, again formulated set up a laboratory in his back garden. Within five as CaSiO3, but also in the Wollaston Medal, award- years he had developed a process for rendering ed annually by the Geological Society (Geological platinum metal malleable, and this is said to have Society of London, see Appendix). ultimately made him a fortune of £30,000. Sir Joseph Barrow provided, in his “Sketches of Wollaston’s process for producing malleable plat- the Royal Society”, a longer and more affectionate inum has been well described (2), including the sketch of Wollaston than he did of the rather more interesting finances of this venture (14–16). remote figure Smithson Tennant, saying that he In November 1802 he was awarded the Copley was one of the most remarkable men of his day Medal, the highest honour of the Royal Society, (17). It was also said, admittedly some time after and for a short period in 1820 he was President of Wollaston’s death, that: the Royal Society, bridging the gap between the He led a solitary life, and was never married .... He long-serving President, Sir Joseph Banks and Sir was however a just and most honourable man, Humphry Davy. candid, open and free from envy with perfect straight- In all, Wollaston published over 50 papers on forwardness; (his) relish for acquiring money with various aspects of chemistry, optics, physiology, the generosity in parting with it when it could be pathology, mineralogy, crystallography, electricity, generously bestowed; the clear intellect, the self- astronomy, mechanics and botany. Prominent reliance, the aversion to interference on the part of among his many innovations was invention of a strangers seem to merit Wollaston as, par excellence, camera lucida and the development of the concept the true English philosopher (13). of equivalent weights. In 1809 he invented a reflecting goniometer which permitted very accu- It is perhaps a measure of him that after the bitter

In 1831, the Geological Society of London, the world’s oldest geological society, instituted the Wollaston Medal, its highest honour, and possibly the most prestigious award for any geologist to receive. It is awarded each year for outstanding achievement in geology. The first Wollaston Medal, made of gold, was awarded to William Smith, see Appendix. While made of gold for some years, the medal was made of palladium from 1846–1860 and again since 1930 Reproduced by courtesy of The Geological Society of London

Platinum Metals Rev., 2003, 47, (4) 177 controversy with Richard Chenevix on the nature of dilute nitric acid, and the residue was then dis- palladium, recounted below, Wollaston seemed to solved in more aqua regia; NaCl was added and the retain no rancour, and entertained him several times solution was evaporated to give the rose-red in 1810 in the Royal Society Dining Club (4, 6). Na3[RhCl6].nH2O. After extraction of this with hot alcohol, zinc was added to precipitate the rhodium The Discovery of Rhodium metal (8). The first official announcement that Wollaston made of his discovery of rhodium was read to the The Discovery of Palladium Royal Society on 24th June 1804, and published in However, Wollaston’s prior discovery of palla- that year, when he described the discovery of: dium is a colourful story (2, 4, 7, 18, 19). Wollaston first mentions his discovery in his notebook for another metal, hitherto unknown, which may not be July 1802 calling the new element simply ‘‘C’’ (2, 4). improperly distinguished by the name of Rhodium, In a later notebook he recalled that this probably from the rose-red colour of a dilute solution of the stood for Ceresium, after the recently discovered metal containing it (8). asteroid Ceres. By August 1802 he had renamed it The metal was named after the Greek ródon (a Palladium rose), although in undated notebooks (4) he refers from a planet that had been discovered nearly at the to it as “N-novm” (perhaps Novum). same time by Dr. Olbers... Platina (a concentrated form of platinum ore) was dissolved in aqua regia and most of the plat- and mentions this in his subsequent full paper on inum removed (as (NH4)2[PtCl6]) by addition of the element (9). This ‘planet’ would be Pallas, later

NH4Cl. Zinc was then added to the filtrate; this shown to be an asteroid (2). resulted in the precipitation of any residual plat- To establish the priority of his work – perhaps inum, some palladium, rhodium, copper and lead. because he was aware that, in particular, the The latter two were removed by dissolution in French chemists Collet-Descotils, Fourcroy and

One of Wollaston’s notebooks showing the page for 14 June 1804, on which he describes the new metal rhodium. Using common salt he evaporated to dryness the remainder of a metallic precipitate after it was washed. Following treatment with alcohol, a rose coloured residue remained. The metal he isolated from this he called Rhodium By permission of the Syndics of Cambridge University Library

Platinum Metals Rev., 2003, 47, (4) 178 The handbill describing palladium which Wollaston published and distributed anonymously in April 1803. It offered for sale “Palladium; or, New Silver a New Noble Metal”. This handbill was later published in Nicholson’s Journal By permission of the Syndics of Cambridge University Library

Vauquelin were pursuing research along similar bium, was to be one of these). However, prior to lines – he adopted an unusual and, in the history of this, in November 1803, Wollaston had privately inorganic elemental discovery, unique stratagem. confided his discovery of palladium to Sir Joseph In April 1803 anonymous advertisements or hand- Banks, apparently for fear that he would be blamed bills were distributed in London offering for sale if Chenevix received the Copley Medal (6, 7). at a shop in Gerrard Street, Soho, ‘‘Palladium, or, The challenge to make palladium was not taken New Silver .a new Noble Metal’’. The handbill up, and in 1805 Wollaston provided an ‘official’ was later published in Nicholson’s Journal (5). announcement of his discovery in a paper which Suspecting a fraud, the entire stock of the mate- he read to the Royal Society on 4th July 1805 (9), rial was bought from the shop by an Irish chemist, although he had made a number of references to Richard Chenevix (1774–1830), for some 15 palladium in his 1804 paper on rhodium (8). After guineas. He claimed that it was an alloy of plat- the 1805 paper (9) it was generally accepted that inum and mercury (20). A number of eminent palladium was indeed a true element. chemists, including Vauquelin, Klaproth and In Wollaston’s optimised procedure for the iso- Gehlen, investigated the material but did not agree lation of palladium he took the solution of platina that the “palladium” was an alloy. An anonymous in aqua regia and removed platinum, as described letter was sent in December 1803, almost certainly above. The filtrate from this was neutralised and by Wollaston, to the editor of Nicholson’s Journal then treated with mercuric cyanide, Hg(CN)2, to (21), offering a reward of £20 to anyone who could give a pale yellow-white precipitate of ‘‘prussiate

“make” palladium in public before three eminent of palladium’’, Pd(CN)2, which on ignition gave chemists (Charles Hatchett, the discoverer of nio- palladium metal (9).

Platinum Metals Rev., 2003, 47, (4) 179 The Wollaston notebook in which he records, probably for the first time, (left page) in July 1802, of palladium as “C”. The right page states: “The upper part of opposite page was written July 1802. I believe the C meant Ceresium a name which I once thought of giving to Palladium” By permission of the Syndics of Cambridge University Library

In his penultimate paper, read as the Bakerian ever since) he did not assign symbols to the ele- Lecture to the Royal Society on 20th November ments. Berzelius originally suggested R for 1828, just one month before his death, Wollaston rhodium but later revised this to Rh; palladium described the method by which he rendered plat- first became Pl, then Pa and finally Pd (2). In his inum malleable and, in a final section, he described remarkable book “Exotic Mineralogy”, published his method of making malleable palladium. This in 1811, Sowerby illustrates three small specimens involved heating Pd(CN)2 with sulfur, followed by given to him by Wollaston of: cupellation in an open crucible with nitre and Native Palladium, nearly pure...... (from) the borax; the residue was subjected to a low red heat Brazilian Platinum (23). whereupon a malleable ingot of palladium metal resulted (22). From 1825 until his death in 1828 Wollaston Over the period 1803 to 1821 it has been calcu- lived at No. 1 Dorset Street, in London. lated that Wollaston isolated some 255 Troy ounces of rhodium and 302 Troy ounces of palladium Rhodium and Palladium from 47,000 ounces of “ore of platina”. Analyses in the Nineteenth Century were recently carried out on samples of Wollaston’s Wollaston recorded two industrial applications palladium and rhodium held by the Science of rhodium and palladium. He used a palladium- Museum in London. These were two samples from gold alloy to make corrosion-resistant graduation ‘‘Faraday’s Chemical Cabinet’’ labelled “Palladium plates for scientific instruments, including the from Dr. Woolaston” (sic) and four rhodium-con- mural circle at the Royal Observatory Greenwich taining samples labelled “Wollaston Relics, My erected by Troughton in 1812. Such alloys were Property, LFG”. The samples of palladium were also used in sextants. He also used a rhodium-tin 89.3 per cent pure (impurities included platinum, alloy to achieve durable tips to pen nibs in the copper and rhodium), while the rhodium content in 1820s and these were sold for sixpence per tip (7). the last four varied from 67.4 to 99.3 per cent This market was later largely supplanted by the (impurities were platinum, palladium and iron) (7). much harder osmiridium alloys (an osmium-iridi- Although Wollaston gave the names rhodium um alloy). The Science Museum, London, keeps and palladium (and these names have been used samples of Wollaston’s rhodium-tin alloy pen nibs.

Platinum Metals Rev., 2003, 47, (4) 180 During Wollaston’s lifetime a “Mr. Johnson of important use of palladium and rhodium, and 79 Hatton Garden” (the metallurgist Percival remains so today. Indeed, the industrial uses of all Norton Johnson (1792–1866), a founder of the pgms increased tremendously during the twen- Johnson Matthey) supplied to a Sheffield steel firm tieth century, especially in the latter half and this material from which two rhodium-iridium-silver- continues today. steel razors were made. These were presented to Michael Faraday (6). Johnson later supplied the Conclusions Geological Society with palladium for the Of the two elements palladium and rhodium, Wollaston Medal (see Appendix). Johnson men- palladium in particular has a remarkable history tions the use of palladium alloys in chronometer and is surely the only element of the 114 we now bearings and in steels in 1837, and of 80% palladi- know that was isolated and then, instead of its dis- um-20% silver alloys in dentistry (24). The use of covery being announced and published in a palladium in dental alloys continues to this day. learned journal, was advertised for sale, causing In 1866, Thomas Graham (1805–1869), who the furore outlined above. Wollaston’s motives in from 1837 to 1854 was Professor of Chemistry at doing this, and the way that he conducted the University College, London, resigning this post to whole affair, still remain obscure. become Master of the Mint, noted that palladium The two metals and their compounds and com- could absorb up to six hundred times its own vol- plexes are, of course, of absorbing scientific ume of hydrogen. At the Royal Mint he cast some interest, and this has long been recognised (thus medallions of hydrogen-containing palladium the Nobel Prize in Chemistry for 2001 was won by which he circulated to his friends. He considered William S. Knowles and Ryoji Noyori for their hydrogen-containing palladium to be an alloy – work on rhodium-catalysed chiral hydrogenation which in a sense it is – and called it ‘‘palladium- reactions (and by K. Barry Sharpless for his chiral hydrogenium’’ (2). oxidation work, including cis-hydroxylations catal- In 1908, Sir William Crookes (1832–1919) per- ysed by osmium tetroxide (27))). suaded Johnson Matthey to ‘fashion’ crucibles of rhodium, iridium, ruthenium and osmium; Appendix Crookes does not record if they succeeded with (a) Iconography. Walker’s excellent “Regency the latter two metals, but he found rhodium to be Portraits” gives information on prints, engravings, busts almost as durable a material as iridium for this pur- and painting of Wollaston (28). The painting by John pose (25). Jackson of 1820 is in the Royal Society (see also (2)). The In the late nineteenth century palladium salts National Portrait Gallery has drawings by John Jackson

(generally Na2[PdCl4]) were used, often but not (1820) and William Brockenden (1830) (see also (4)) and always in conjunction with K2[PtCl4], for the pro- holds two camera lucida sketches by Chantrey for duction of palladium or palladium-platinum Wollaston’s bust. The bust itself (1830), in marble, by photographic prints. These have richer tones and Francis Chantrey, is in the Royal Institution, and the more permanence than silver images. Such plaster model is kept in the Ashmolean Museum, processes are still used occasionally (26). Oxford, the source of the portrait on the obverse of the The catalytic properties of the pgms were first Wollaston Medal. The Royal Society, Royal Institution, noted in the nineteenth century. Humphry Davy and the Geological Society all have engravings or draw- first observed heterogeneous catalysis in 1817, ings of him. with platinum, when he found that a mixture of (b) The Wollaston Medal. Wollaston became a mem- coal gas and air over platinum wire caused the wire ber of the Geological Society in 1812. Two weeks before to glow. Later, Thénard showed that powdered his death in 1828 he left the Society £1,000 for research rhodium, palladium and iridium catalysed the in geology. The Council of the Geological Society used combination of hydrogen and oxygen (2). the income for the purchase of a die for a medal to be In the twentieth century catalysis became an called after him. At first it was cast in gold but later

Platinum Metals Rev., 2003, 47, (4) 181 (1846–1860) in palladium. The palladium was acquired plaque was erected on that house by the Geological by Percival Norton Johnson of Hatton Garden, also a Society inscribed ‘‘William Hyde Wollaston (1766–1828 Fellow of the Society. The palladium however damaged Natural Philosopher, lived here 1801–1825’’; see refer- the dies, and in 1880 new dies were made, after which ence (6) for a photograph. This site of the building is using gold was resumed. In 1930 the Society reverted to now a car park; and the plaque is housed in the archives using palladium for this most prestigious award in geol- of the Geological Society. ogy. The Medal is awarded annually for outstanding From 1825 until his death in 1828 he lived at No. 1 geological research. It was first awarded on 20 June 1832 Dorset Street, near Manchester Square. Charles Babbage, (the official award was made on 18 February 1831 but the inventor of the forerunner of the computer, also the medal was not ready) to William Smith, the ‘Father lived in the house from 1829 to his death in 1871. The of English Geology’, who made the first reliable geolog- house (which is not the original) carries a plaque to ical map of Britain, using the principles of fossil Babbage. succession. Other early holders were Sir Henry de la Beche (1855), Charles Darwin (1859), Sir Roderick Bibliographies Murchison (1864) and T. H. Huxley (1876) (29). The magisterial bibliographies by J. L. Howe Wollaston’s profile, taken from the Chantrey bust, is on cover the period 1748 to 1950 (30). The author the obverse, while the reverse is inscribed “Geological wrote a survey of the chemistry of rhodium, cov- Society of London” with the recipient’s name enclosed ering the literature up to 1967 (31), and on the between laurel and palm branches (29). non-organometallic chemistry of rhodium (32) and (c) Residences. Wollaston lived much of his life in palladium (33). F. R. Hartley wrote a book on the London. Despite the demolition of many old buildings in chemistry of palladium and platinum (34). London, streets tend to retain their names. It is therefore More up-to-date, though less comprehensive is rather sad that the names of the first two streets in which a short book on the six platinum group metals by Wollaston lived have been changed, and his houses lost. Cotton (35), and the ‘‘Encyclopedia of Inorganic From 1797 to 1801 he lived at 18 Cecil Street, where he Chemistry’’ has useful articles on the coordination perfected some of his platinum purification procedures; and organometallic chemistry of rhodium (36) and Cecil Street is now Ivy Bridge Lane, a narrow private palladium (37). road leading from the Strand down to the Savoy at Savoy Place. He moved in 1801 to 14 Buckingham Street, not Acknowledgements the charming Buckingham Street close to Ivy Bridge Andrew Mussell, the archivist of the Geological Society and Lane, but a small street near Park Crescent, Regents his colleague Gordon Herries-Davies; Professor Mel Usselman, University of Western Ontario, for a preprint of reference 14; Park, now called Greenwell Street: here his rhodium and and Professor J. Marshall, Duke University, Texas, for help in palladium work was probably done. On July 4 1934 a tracing Wollaston’s London residences.

References 1 http://www.iupac.org/news/archives/2003/nam- 9 W. H. Wollaston, Phil. Trans. Roy. Soc., 1805, 95, 316; ing110.html J. Nat. Philos., Chem. Arts, 1805, 10, 34 2 D. McDonald and L. B. Hunt, “A History of 10 Smithson Tennant, Phil. Trans. Roy. Soc., 1804, 94, Platinum and its Allied Metals”, Johnson Matthey, 411; J. Nat. Philos., Chem. Arts, 1805, 10, 24 London, 1982 11 D. McDonald, Platinum Metals Rev., 1966, 10, (3), 101 3 D McDonald, Platinum Metals Rev., 1964, 8, (2), 67; 12 P. J. Hartog and C. H. Lees, “Dictionary of National V. N. Pitchkov, ibid., 1996, 40, (4), 181; K. K. Klaus, Biography”, Oxford University Press, 1921, Vol. 21, J. Pharm. Khim., 1845, 8, 381 p. 782 4 L. F. Gilbert, Notes Rec. Roy. Soc. London, 1952, 9, 310 13 G. Wilson, “Religio Chemici”, MacMillan, London, 5 Anon., J. Nat. Philos., Chem. Arts, 1803, 5, 136 1862, p. 253 6 L. F. Gilbert, “Platinum Metals Exhibition”, 14 M. C. Usselman, Ann. Sci., 1980, 37, 253; M. C. Institution of Metallurgists, London, 1953 Usselman, ‘Smithson Tennant: the innovative and 7 M. C. Usselman, Ann. Sci., 1978, 35, 551 eccentric 8th Professor of Chemistry’ in “Three 8 W. H. Wollaston, Phil. Trans. Roy. Soc., 1804, 94, 419; Centuries of Chemistry at Cambridge”, ed. M. J. Nat. Philos., Chem. Arts, 1805, 10, 3 Archer, Cambridge University Press, in press

Platinum Metals Rev., 2003, 47, (4) 182 15 M. C. Usselman, Platinum Metals Rev., 1978, 22, (3), 100 31 W. P. Griffith, “The Chemistry of the Rarer 16 J. A. Chaldecott, Platinum Metals Rev., 1979, 23, (3), 112 Platinum Metals (Os, Ru, Ir and Rh)”, Wiley 17 Sir John Barrow, “Sketches of the Royal Society and Interscience, London, 1968 the Royal Society Club”, John Murray, London, 32 W. P. Griffith, H. Jehn, J. McCleverty, Ch. Raub and 1849, p. 54 S. D. Robinson, ‘Rhodium’, in “Gmelin Handbook 18 I. E. Cottington, Platinum Metals Rev., 1991, 35, (3), 141 of Inorganic Chemistry”, eds. W. P. Griffith and K. 19 B. I. Kronberg, L. L. Coatsworth and M. C. Swars, Springer-Verlag, Berlin, 1982, Vol. 64, Suppl. Usselman, Ambix, 1981, 28, 20 Vol. B1; W. P. Griffith, J. McCleverty and S. D. Robinson, ibid., 1983, Vol. 64, Suppl. Vol. B2; W. P. 20 R. Chenevix, Phil. Trans. Roy. Soc., 1803, 93, 290; Griffith, J. McCleverty and S. D. Robinson, ibid., ibid., 1804, 7, 159; ibid., 1805, 95, 163, 182 1984, Vol. 64, Suppl. Vol. B3 21 Anon., J. Nat. Philos., Chem. Arts, 1804, 7, 75, 159 22 W. Wollaston, Phil. Trans. Roy. Soc., 1829, 119, 1 33 W. P. Griffith, J. McCleverty, S. D. Robinson and K. Swars, ‘Palladium’, in the “Gmelin Handbook of 23 J. Sowerby, “Exotic Mineralogy: or, Coloured Inorganic Chemistry”, eds. W. P. Griffith and K. Figures of Foreign Minerals, as a Supplement to Swars, Springer Verlag, Berlin, 1989, Vol. 65, Suppl. British Mineralogy”, Benjamin Meredith, London, Vol. B2 1811, p. 69 and facing p. 69 24 P. N. Johnson and W. A. Lampadius, J. Prakt. Chem., 34 F. R. Hartley, “The Chemistry of Palladium and 1837, 11, 309 Platinum”, Applied Science Publishers, London, 25 W. Crookes, Proc. Roy. Soc., 1908, 80A, 535 1973 26 D. Arentz, “Platinum and Palladium Printing”, 35 S. A. Cotton, “Chemistry of Precious Metals”, Focal Press, Oxford, Boston, MA, 2000 Blackie Academic, London, 1997 27 http://www.nobel.se/chemistry/laureates/2001/ 36 F. H. Jardine, in “Encyclopedia of Inorganic index.html; T. J. Colacot, Platinum Metals Rev., 2002, Chemistry”, ed. R. B. King, Wiley, London, 1994, 46, (2), 82 Vol. 7, p. 3467; J. T. Mague, ibid., 1994, Vol. 7, p. 28 R. Walker, “Regency Portraits”, National Portrait 3489 Gallery, London, 1985, Vol. 1, p. 568 (text); Vol. 2, plates pp. 1417–1422 37 A. C. Albeniz and P. Espinet, in “Encyclopedia of 29 H. B. Woodward, “The History of the Geological Inorganic Chemistry”, ed. R. B. King, Wiley, Society of London”, Geological Society, London, London, 1994, Vol. 6, p. 3023; J. W. Suggs, ibid., 1907 1994, Vol. 6, p. 3010 30 J. L. Howe and H. C. Holtz, “Bibliography of the Metals of the Platinum Group Metals 1748–1917”, The Author U.S. Geol. Survey Bull. 694, Government Printing Office, Washington, 1919; J. L. Howe and staff of Bill Griffith is Professor of Inorganic Chemistry at Imperial College, Baker & Co., “Bibliography of the Platinum Metals London. He has considerable experience of the pgms, particularly 1918–1930”, Baker Inc., Newark, NJ, 1947; ibid., for of ruthenium and osmium. He has published over 250 research papers, many describing complexes of these metals as catalysts 1931–1940 (publ. 1949); ibid. for 1941–1950 (publ. for specific organic oxidations. He has written seven books on the 1956). Futher details see G. B. Kauffmann, Platinum platinum metals, and is the Secretary of the Historical Group of the Metals Rev., 1972, 16, (4), 140 Royal Society of Chemistry. Magnetic Field Effects on Benzene Photodegradation

Since nuclear and electronic spin polarisation phe- Benzene conversion and CO2 production were monitored. nomena during chemical reactions were discovered, On application of magnetic field (59.42 mT) benzene magnetic field effects on the kinetics of chemical reac- conversion increased from 15.5 to 18%, and CO2 pro- tions, especially those with free radicals, have been duction increased from 52 to 175 ppm. On removing the examined. As heterogeneous photocatalytic reactions in field benzene conversion fell to 4%, and CO2 production the presence of O2 produce free radicals and radical ions fell to its initial value. Low field intensities suppressed the reactions may be affected by magnetic fields. benzene conversion, but at fields > 52 mT benzene con-

Scientists from Fuzhou University, P. R. China, have version increased rapidly. CO2 production increased now reported the effects of magnetic fields on the UV over the whole field range. photocatalytic degradation at 65ºC, of benzene using a Removal and reapplication of the field produced a synthesised 0.5% Pt/TiO2 catalyst (W. Zhang, X. Wang similar result, but putting fresh catalyst into a field pro- and X. Fu, Chem. Commun., 2003, (17), 2196–2197). duced little improvement. Without UV, Pt or catalyst, no The catalyst was placed in a quartz tube, surrounded reaction occurred. The results may be linked to decom- by an electromagnetic field vertical to the axes in the position of intermediate species on Pt. Reasons for the photoreactor, and benzene was supplied at 20 ml min–1. phenomena are unknown; further studies are in progress.

Platinum Metals Rev., 2003, 47, (4) 183 ABSTRACTS of current literature on the platinum metals and their alloys

PROPERTIES Palladium(II) Complexes of the Reducing Sugars Local Reactivity of Thin Pd Overlayers on Au D-Arabinose, D-Ribose, rac-Mannose, and Single Crystals D-Galactose A. ROUDGAR and A. GROß, J. Electroanal. Chem., 2003, 548, P. KLÜFERS and T. KUNTE, Chem. Eur. J., 2003, 9, (9), 121–130 2013–2018 II The local reactivity of thin pseudomorphic Pd over- An aqueous solution of [(en)Pd (OH)2] (en = ethyl- layers on Au(111) and (100) single crystal surfaces was enediamine) reacts with the title monosaccharides to studied by periodic density functional theory calcula- form dimetallated aldose complexes, when the molar tions within the generalised gradient approximation. ratio of Pd and sugar is ³ 2:1. In the Pd2 complexes, The adsorption energies of atomic H and of CO as a the aldoses are tetra-deprotonated and act as bisdiola- microscopic probe of the reactivity were determined. to complexes. Two crystalline pentose complexes The lattice expansion (5%) of the pseudomorphic Pd were isolated, along with two hexose complexes. On films and the interaction of the Pd films with the Au substitution of en by isopropylamine, monometalla- substrate increased the reactivity of the overlayers. tion of the aldoses in the 1,2-position was observed.

The Superelasticity of TiPdNi High Temperature Carbenes. Pincers, Chelates, and Abnormal Shape Memory Alloy Binding Modes J. WU and Q. TIAN, Intermetallics, 2003, 11, (8), 773–778 R. H. CRABTREE, Pure Appl. Chem., 2003, 75, (4), 435–443 Routes to pincer and chelate carbene complexes of In Ti51Pd30Ni19 (1), superelasticity was found for the first time. The recoverable superelastic strain was 7% Pd, Rh, and Ir include double geminal CH activation, without failure of the specimen. The shape memory metallation and CH activation. Abnormal binding via effect at room temperature was evaluated as 7.2% imidazole C5 can occur, and ion pairing can strongly with the recovery rate of 100%. Superelasticity was influence C2 vs. C5 binding. Prior ligand binding via obtained by introducing large numbers of disloca- pyridine N before metallation is not essential. (27 tions and precipitates in the matrix of (1). Refs.)

CHEMICAL COMPOUNDS ELECTROCHEMISTRY Coordination Isomerism in Salicylhydroxamate Electroreduction Behavior of Dinitrogen over Complexes of Platinum(II) and Palladium(II) Ruthenium Cathodic Catalyst W. HENDERSON, C. EVANS, B. K. NICHOLSON and J. FAWCETT, S.-Y. ZHANG, X.-Y. ZHANG, Z.-S. ZHANG, Y. KONG and Dalton Trans., 2003, (13), 2691–2697 S.-N. HUA, Chem. Lett., 2003, 32, (5), 440–441 A catalyst of chemically deposited Ru loaded on Reaction of cis-[PtCl2(PPh3)2] with salicylhydroxam- ic acid (1) and trimethylamine (2) gave O,O¢-bonded active C was used to reduce N2 electrochemically in [Pt{OC(=NO)C H OH}(PPh ) ], but [PtCl (cod)] gave aqueous solution at ambient temperature and pressure. 6 4 3 2 2 A conventional three-electrode cell with Ru/C cathode N,O-bonded [Pt{OC6H4C(O)NOH}(cod)] (3). Ligand substitution of (3) gave other N,O-bonded as working electrode, Pd/C anode as counter elec- complexes such as [Pt{OC H C(O)NOH}(PPh ) ]. trode, and Hg/HgO/NaOH as reference electrode 6 4 3 2 were used. A peak with many shoulders correspond- Reaction of K2PtCl4 with EPh3 (E = As, Sb), (1) and (2) gave products of different structures: AsPh gave ing to the reduction of N2 to NH3 was first observed 3 in the difference linear sweep voltammogram. [Pt{OC(=NO)C6H4OH}(AsPh3)2], while SbPh3 gave [Pt{OC6H4C(O)NOH}( SbPh3)2], respectively. Ruthenium Oxide-Added Quartz Iron Phosphate as 4+ Structure and Bonding of Pd@[Bi10] in the a New Intercalation Electrode in Rechargeable

Subbromide Bi14PdBr16 Lithium Cells M. RUCK, V. DUBENSKYY and T. SÖHNEL, Angew. Chem. Int. F. CROCE, A. D’EPIFANIO, P. REALE, L. SETTIMI and B. SCROSATI, Ed., 2003, 42, (26), 2978–2982 J. Electrochem. Soc., 2003, 150, (5), A576–A581 The high-temperature reaction (1270 K) of the Anhydrous, composite a-quartz FePO4, with added intermetallic phase Bi2Pd with additional Bi and Br2 RuO2, can be used as an intercalation electrode for yields grey lustrous platelets of Bi14PdBr16 (1). Single- rechargeable Li cells. The dispersion of RuO2 parti- crystal X-ray diffraction of (1) showed it to be a cles enhances the FePO4 interparticle electronic 4+ complex salt that consists of cluster cations [PdBi10] conductivity, thus improving the kinetics of the elec- 1 4– (2) and anionic octahedra chains ¥[Bi4Br16 ]. (2) is a trochemical processes. The charge-transfer resistance pentagonal antiprism of 10 Bi atoms with a Pd atom of the RuO2-added FePO4 electrodes was significant- at their centre. ly lower than FePO4 electrodes without RuO2.

Platinum Metals Rev., 2003, 47, (4), 184–187 184 PHOTOCONVERSION APPARATUS AND TECHNIQUE Luminescent Platinum(II) Terpyridyl-Capped Characterization of Platinum Nanoparticle- Carbon-Rich Molecular Rods–An Extension from Embedded Carbon Film Electrode and Its Molecular- to Nanometer-Scale Dimensions Detection of Hydrogen Peroxide V. W.-W. YAM, K. M.-C. WONG and N. ZHU, Angew. Chem. Int. T. YOU, O. NIWA, M. TOMITA and S. HIRONO, Anal. Chem., Ed., 2003, 42, (12), 1400–1403 2003, 75, (9), 2080–2085 [Pt(t Bu3-tpy)(CºC)nPt(t Bu3-tpy)](X)2 ((1): n = 1, X A flat, uniform film (1) of 6.5% Pt nanoparticles = OTf; (2): n = 2, X = OTf; (3): n = 4, X = PF6; tBu3- embedded in a graphite-like C matrix was prepared tpy = 4,4¢,4²-tri-tert-butyl-2,2¢:6¢,2²-terpyridine) were by the RF sputtering method. When used as an elec- synthesised. In contrast to the red shift commonly trode (1) is very active for H2O2 electrooxidation. found in organic polyynes and other metal-alkenyl When modified with glucose oxidase the electrode systems, a blue shift in the transition energy was responded rapidly to glucose with a more stable base- observed in the electronic absorption and emission line current than at a Pt bulk electrode sensor. (1) going from (1) to (2) to (3). This was due to increas- coupled with microbore liquid chromatography and a ing the extent of p conjugation of the alkynyl bridge. postcolumn enzyme reactor gave a lower detection limit for acetylcholine and choline. Synthesis and Spectral Properties of 2-Pyridyl N-Methyl-2-imidazolyl Ketone Complexes of CO Sensitivity of the PtO/SnO2 and PdO/SnO2 Iridium(III) Layer Structures: Kelvin Probe and XPS Analysis G. KISS, V. K. JOSEPOVITS, K. KOVÁCS, B. OSTRICK, W. L. HUANG, M. C. TSENG, J. R. LEE and X. Y. CHEN, Inorg. Chim. Acta, 2003, 349, 97–103 M. FLEISCHER, H. MEIXNER and F. RÉTI, Thin Solid Films, 2003, + 436, (1), 115–118 K[Ir(pik)Cl4] and [Ir(pik)(phen)Cl2] (1) show high intensity bands in the UV region. At 77 K, (1) in The CO sensitivity of SnO2 thick layers impregnat- EtOH/MeOH (4:1 v/v) shows a structural emission ed with Pt(NH3)2(NO2)2 and Pd(NH3)2(NO2)2 was with a single vibrational progression of 1090 cm–1. measured by following the work function change, at The luminescence lifetime at the 474 nm emission is 90ºC. The complexes were decomposed, by heat 9.7 µs and the emission energy becomes smaller while treatments in air, at 150–350ºC. The maximum CO the solvent’s polarity increases. sensitivity, the optimal response and recovery times, as measured by a Kelvin probe, were attained when PtO or PdO were present on the surface. ELECTRODEPOSITION AND SURFACE COATINGS HETEROGENEOUS CATALYSIS Chemical Vapor Deposition of Macroporous Platinum-Containing Polymeric Catalysts in Direct Platinum and Palladium–Platinum Alloy Films by L-Sorbose Oxidation Using Polystyrene Spheres as Templates E. SULMAN, V. MATVEEVA, L. BRONSTEIN, A. SIDOROV, M. FENG and R. J. PUDDEPHATT, Chem. Mater., 2003, 15, (14), N. LAKINA, S. SIDOROV and P. VALETSKY, Green Chem., 2003, 2696–2698 5, (2), 205–208 Self-assembled polystyrene latex spheres (1) (500 Impregnation of hypercrosslinked polystyrene nm diameter on Al or Cu) were used as templates for (HPS) with THF or MeOH solutions containing the low-temperature CVD (70ºC) of Pt and Pt-Pd H2PtCl6 caused Pt(II) complexes to form within the films. The precursors included [PtMe2(COD)] and nanocavities of the HPS. The HPS-Pt-THF complex [Pd(hfac)2]. For Pt deposition, a catalytic amount of gave the highest selectivity (98% at 100% conversion) [Pd(C4H7)(hfac)] was required to initiate CVD. After during the catalytic oxidation of L-sorbose in H2O. the CVD, (1) are removed by pyrolysis at 400–450ºC Electron micrographs of the catalyst isolated after the to give the structured metal films. induction period showed enlarged Pt nanoclusters.

Reduced Sulfur-Terminated Silanes to Promote Selective Oxidation of Alcohols to Carbonyl the Interaction of Palladium(II) Hexafluoroacetyl- Compounds and Carboxylic Acids with Platinum acetonate with Dielectric Surfaces Group Metal Catalysts J. J. SENKEVICH, C. J. MITCHELL, G.-R. YANG and T.-M. LU, R. ANDERSON, K. GRIFFIN, P. JOHNSTON and P. L. ALSTERS, Colloids Surf. A: Physicochem. Eng. Aspects, 2003, 221, (1–3), Adv. Synth. Catal., 2003, 345, (4), 517–523 29–37 High throughput screening techniques were used to II Pd (hfac)2 (1) readily interacts with –SS– and identify catalytic activity and product selectivity for –SSSS– species obtained via silane self-assembled the title reaction. Using air as oxidant and H2O as sol- chemistry, but gives little or no interaction with vent, 5% Pt, 1% Bi/C was identified as an efficient hydroxylated SiO2 surfaces. The chemisorption under catalyst for the transformation of 2-octanol to 2- CVD-like conditions, where (1) was mixed with H2, octanone and 1-octanol to octanoic acid. For Ru/C, showed similar results as that without H2. Mercapto- the incorporation of Pt increased conversion, but at silane multilayers gave most deposition of Pd. the expense of aldehyde selectivity.

Platinum Metals Rev., 2003, 47, (4) 185 Selective Removal of a Benzyl Protecting Group Sequential Azomethine Imine Cycloaddition– in the Presence of an Aryl Chloride under Palladium Catalysed Cyclisation Processes Gaseous and Transfer Hydrogenolysis Conditions C. W. G. FISHWICK, R. GRIGG, V. SRIDHARAN and J. VIRICA, Tetrahedron, 2003, 59, (24), 4451–4468 J. LI, S. WANG, G. A. CRISPINO, K. TENHUISEN, A. SINGH and J. A. GROSSO, Tetrahedron Lett., 2003, 44, (21), 4041–4043 The in situ generation of azomethine imines from The selective removal of a benzyl protecting group aryl/heteroaryl aldehydes and N,N¢-disubstituted in the presence of an aryl chloride in the synthesis of hydrazines followed by cycloaddition to N-methyl- a quinolinone can be achieved using Pd/C under maleimide gives pyrazolidines. These undergo Pd(0) gaseous and transfer hydrogenolysis conditions. The catalysed cyclisation involving the aldehyde and addition of chloride salts such as NaCl to the deben- hydrazine substituents, with formation of 6–8 mem- zylation reaction resulted in excellent selectivity. The bered rings in good yield. The cyclisation catalyst chloride salts suppress an undesired dehalogenation system was either Pd(OAc)2/PPh3/NEt4Cl/K2CO3 reaction. or Pd(OAc)2/PPh3/TlOAc.

Dehalogenation of Trihalomethanes in Drinking Iridium-HetPHOX Complexes for the Catalytic Water on Pd–Feº Bimetallic Surface Asymmetric Hydrogenation of Olefins and Imines P. G. COZZI, F. MENGES and S. KAISER, Synlett, 2003, (6), E. GUASP and R. WEI, J. Chem. Technol. Biotechnol., 2003, 78, (6), 654–658 833–836 Degradation of trihalomethanes (THMs), byprod- Heterocyclic phosphino oxazolines (HetPHOX) derived from thiophene and benzo[b]thiophene form ucts of potable H2O disinfection, by Pd-treated Fe granules (1), Pd–Feº, was studied in a flow-through highly active Ir complexes for the catalytic enantiose- column system. Columns were loaded with Torpedo lective hydrogenation of olefins and imines. When and Silica sands plus anthracite mixed with (1) at a treated with Na tetrakis[3,4-bis(trifluoromethylphen- 10:1 ratio (w/w). A single passage of THM samples yl)]borate, the Ir-HetPHOX complexes gave com- (50–200 ppb) through the column resulted in greater plete conversion of olefins after 2–4 h at catalyst than 90% disappearance of THMs with one or more loadings of 1–2%. Enantioselectivities were generally Br atoms (CHCl Br, CHClBr and CHBr ), but the excellent: £ 99% ee for (E)-1,2-diphenyl-1-propene. 2 2 3 An imine was hydrogenated in £ 86% ee employing degradation of CHCl3 was slower. The column could be regenerated with simple acid washing. No measur- 0.1 mol% of catalyst. able Pd and Fe concentrations were detected in the column effluents over 3–4 weeks, indicating that (1) Iridium-Catalysed Labelling of Anilines, is stable in the column. Benzylamines and Nitrogen Heterocycles Using Deuterium Gas and Cycloocta-1,5-dienyliridium(I) HOMOGENEOUS CATALYSIS 1,1,1,5,5,5-Hexafluoropentane-2,4-dionate M. J. HICKEY, J. R. JONES, L. P. KINGSTON, W. J. S. LOCKLEY, Hydrogenation of Olefins Using Ligand-Stabilized A. N. MATHER, B. M. McAULEY and D. J. WILKINSON, Tetrahedron Palladium Nanoparticles in an Ionic Liquid Lett., 2003, 44, (20), 3959–3961 J. HUANG, T. JIANG, B. HAN, H. GAO, Y. CHANG, G. ZHAO and Anilines, benzylamines and nitrogen heterocycles

W. WU, Chem. Commun., 2003, (14), 1654–1655 can be readily deuterated by exchange with D2 gas Phenanthroline ligand-protected Pd nanoparticles and the title Ir(I) complex. The isotopic exchange is (1), in the ionic liquid 1-n-butyl-3-methylimidazolium effective in dimethylformamide or dimethylacetamide, hexafluorophosphate, were shown to be a very active hence it can also be applied to the deuteration of and selective catalyst system for the hydrogenation of polar compounds such as pharmaceuticals. Isotope olefins. Low temperature (20–60ºC) and low pressure incorporation is rapid and yields ortho-regiospecificity. of H2 (1 bar) were used. (1) can be reused many times, without reducing the activity. The diameters of Benchmarking of Ruthenium Initiators for the (1) are in the range of 2–5 nm. ROMP of a Norbornenedicarboxylic Acid Ester S. DEMEL, W. SCHOEFBERGER, C. SLUGOVC and F. STELZER, Preparation of a Series of Aryl Isonipecotic Acids J. Mol. Catal. A: Chem., 2003, 200, (1–2), 11–19 Using Microwave Irradiation A kinetic study of the ROMP of (±)-exo,endo-bicy- S. ANTANE, Synth. Commun., 2003, 33, (12), 2145–2149 clo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diethyl ester Rapid parallel synthesis of aryl isonipecotic acids (1) with Ru benzylidenes gave values for the rates of ini- was achieved by microwave irradiation of a Pd catal- tiation and of propagation of the initiators. These ysed coupling amination reaction of an amino ester were correlated to the molecular weight and polydis- t with aryl bromides. Pd2(dba)3/BINAP/NaO Bu was persity of the isolated polymers. The classical ‘first used as the catalyst system. The amount of solvent generation Grubbs catalyst’ was the only initiator to (toluene) was kept to a minimum. (1) are used in the give virtually monodisperse polymers, while N-hetero- preparation of a wide range of potential drug agents cyclic carbene-based initiators polymerised at a prop- such as anticoagulants, antimicrobial agents and sero- agation rate much higher than the initiation rate giving toninergic/dopaminergic receptor antagonists. polymers with a wider molecular weight distribution.

Platinum Metals Rev., 2003, 47, (4) 186 FUEL CELLS ELECTRICAL AND ELECTRONIC Formation, Microstructural Characteristics and ENGINEERING Stability of Carbon Supported Platinum Catalysts Diffusion Barrier Performance of Novel RuTiN for Low Temperature Fuel Cells Material for High-Density Volatile Memory E. ANTOLINI, J. Mater. Sci., 2003, 38, (14), 2995–3005 Capacitor The method for preparation of Pt/C electrocata- D. S. YOON, J. S. ROH, S.-M. LEE and H. K. BAIK, Acta Mater., lysts influences the choice of the C support and its 2003, 51, (9), 2531–2538 pretreatment. The microscopic distribution of Pt on Electrical properties linked to the oxidation of TiN the C support is dependent on the method of prepa- and RuTiN films in diffusion barrier material were ration and the characteristics of the substrate. High examined. The TiN film (1) barrier in a sputtered- Pt uniformity, low Pt content in the catalyst and/or (Ba,Sr)-TiO3 simple stack-type structure was partially C with high resistance to corrosion are reported to oxidised in the as-deposited state and almost com- improve Pt particle stability. (85 Refs.) pletely oxidised at 550ºC, degrading the capacitance. However, a RuTiN (2) barrier was not oxidised at Conducting Polymeric Nanotubules as High £ 600ºC, and had capacitance > 30 fF/cell, although –9 Performance Methanol Oxidation Catalyst Support the leak current was very high (~ 10 A/cell) due to B. RAJESH, K. R. THAMPI, J.-M. BONARD, H. J. MATHIEU, the low work function (4.43 eV). Thus, for a high- N. XANTHOPOULOS and B. VISWANATHAN, Chem. Commun., density volatile capacitor, (2) had a better O diffusion 2003, (16), 2022–2023 barrier performance than (1). Pt nanoparticle-supported conducting nanotubules of polypyrrole (1) prepared by a template method All Solid-State Rechargeable Thin-Film showed excellent catalytic activity for the electrooxi- dation of MeOH in comparison to Pt/polypyrrole. Microsupercapacitor Fabricated with Tungsten MeOH oxidation is a reaction of importance for the Cosputtered Ruthenium Oxide Electrodes development of DMFCs. (1) can also be employed H.-K. KIM, S.-H. CHO, Y.-W. OK, T.-Y. SEONG and Y. S. YOON, for H oxidation in PEMFCs. J. Vac. Sci. Technol. B, 2003, 21, (3), 949–952 2 An all solid-state thin-film microsupercapacitor (TFSC) was fabricated with W cosputtered RuO Structural, Chemical, and Electronic Properties of 2 electrodes (W-RuO2) and Li2.94PO2.37N0.75 electrolyte. Pt/Ni Thin Film Electrodes for Methanol The room-temperature charge-discharge behaviour Electrooxidation of the TFSC was similar to that of a bulk-type super- K.-W. PARK, J.-H. CHOI and Y.-E. SUNG, J. Phys. Chem. B, 2003, capacitor. The W-RuO2-based TFSC exhibited a 107, (24), 5851–5856 higher discharge specific capacitance and more stable

Pt/Ni thin film electrodes (1) were fabricated by e- cyclability, than a RuO2-based TFSC. beam evaporation of metal layers and rapid thermal annealing. The structural, chemical and electronic properties of annealed (1) were classified as: Pt-dom- MEDICAL USES inant (as-deposited Pt/Ni or 200ºC Pt/Ni); Pt-based Electrochemical and Surface Studies on the (300ºC Pt/Ni) (2); and Ni-dominant (500ºC Pt/Ni). Passivity of a Dental Pd-Based Casting Alloy in (1) were comparable with Pt/Ni (3:1), (1:1) and (1:3) nanoparticles, respectively, synthesised by borohy- Alkaline Sulphide Solution K. ENDO, H. OHNO, K. MATSUDA and S. ASAKURA, Corros. Sci., dride reduction for use in MeOH electrooxidation in 2003, 45, (7), 1491–1504 a DMFC. (2) showed the highest catalytic activity in The alloy Pd-25Ag-18Cu-12Au (1) exhibited higher MeOH electrooxidation. resistance to corrosion and tarnish in Na2S solution (2) at 37ºC than Ag-20Pd-18Cu-12Au. XPS indicated Pt–Ru and Pt–Ru–P/Carbon Nanocomposites: the presence of a thin PdS film, which is responsible Synthesis, Characterization, and Unexpected for the passivity of (1) in (2). These properties make Performance as Direct Methanol Fuel Cell (1) suitable for use in dental casting restoration. (DMFC) Anode Catalysts W. D. KING, J. D. CORN, O. J. MURPHY, D. L. BOXALL, E. A. KENIK, Laser Weld: Microstructure and Corrosion Study K. C. KWIATKOWSKI, S. R. STOCK and C. M. LUKEHART, J. Phys. of Ag–Pd–Au–Cu Alloy of the Dental Application Chem. B, 2003, 107, (23), 5467–5474 M. L. SANTOS, H. A. ACCIARI, L. C. O. VERCIK and A. C. Six Pt-Ru/C nanocomposites (1) were prepared, GUASTALDI, Mater. Lett., 2003, 57, (13–14), 1888–1893 using five different Pt,Ru-bimetallic precursors. (1) The title alloy for use in dental implant prostheses without P contain Pt-Ru nanocrystals that are highly was examined before and after laser welding. The dispersed on the C. However, (1) with P, Pt-Ru-P/C, weld area had a refined microstructure derived from contain f.c.c. Pt-Ru alloy nanocrystals and primitive the high speed cooling, while the base metal away cubic nanocrystals of PtRuP2. (1) containing substan- from the weld area had a coarse fusion microstruc- tial amounts of nano-PtRuP2 performed as well as ture. Electrochemical studies indicated that the weld commercial (1) as the anode catalyst in DMFCs. area had superior corrosion resistance.

Platinum Metals Rev., 2003, 47, (4) 187 NEW PATENTS CHEMICAL COMPOUNDS Organic Electroluminescence Device NIPPON HOSO KYOKAI Japanese Appl. 2003/086,376 Polymeric Transition Metal Complexes An organic electroluminescence device with a high 6,605,200 THERASENSE INC U.S. Patent luminous efficiency contains an organic, luminous A novel polymeric metal complex with Os, Ru, Fe, layer, which has an organic phosphorescent content etc., has a polymeric backbone; a plurality of spacers, formed by mixing two kinds of Ir complexes. The each being covalently coupled to and extending from organic layer is laminated on a transparent glass sub- the polymeric backbone and including a non-cyclic strate and coated with a transparent electrode and a functional group; and a plurality of transition metal metal electrode, for instance of Mg. The Ir complex- complexes. These redox polymers can carry electrons es become the centre of the emission and give between an enzyme and an electrode in a sensor. phosphorescence over the visible region.

APPARATUS AND TECHNIQUE Light Emission Measuring Device KIKKOMAN CORP Japanese Appl. 2003/088,398 Polymer Gel Hybrid Solar Cells A small and lightweight device for measuring the SONY INT. (EUROPE) GmbH World Appl. 03/054,894 A polymer gel hybrid solar cell (1) includes a back- contamination of a specimen by light emission com- electrode; a polymer gel electrolyte of nanoparticles prises a chamber, a low sensitive light-receiving (2–25 nm) and redox couple; and Ru dye sensitised IrGaAs photodiode (1), etc., for receiving light emit- ted from an examination tool and a processor to porous TiO2. (1) can reach a light-to-energy conver- sion efficiency of £ 9.2% with 100 mW cm–2, and £ process signals from (1). The contaminant in the 14.1% with reduced light intensity of 33 mW cm--2. specimen is made to emit light with a luminescent reagent containing an adenosine triphosphate-repro- ducing enzyme such as pyruvate phosphate dikinase. Oxygen Sensor The emission is measured with (1). KYOCERA CORP U.S. Appl. 2003/0,146,093

An O2 sensor (1) contains a sensing element com- prising a solid ZrO2 electrolytic substrate shaped as an HETEROGENEOUS CATALYSIS elongated plate, and a Pt measuring electrode (2) and Catalytic Autothermal Steam Reforming a Pt reference electrode formed on the ends of the OMG AG & CO KG European Appl. 1,314,688 opposing surfaces. (2) has an area of 8–18 mm2, and Catalytic autothermal steam reforming of alcohols the sensing element is 2.0–3.5 mm wide at the end of with ³ 2C atoms, involves directing an educt mixture the substrate. (1) has excellent gas response perfor- of the alcohols, O2 and H2O or steam, heated to a mance, can be quickly heated and is small in size. preheat temperature, over a Pt group metal catalyst

supported on Al2O3, SiO2, TiO2 or their mixed oxides Electrochemiluminescence in Detecting Analytes and zeolites, for example, 1 g l–1 Rh/honeycomb car- ROCHE DIAGNOSTICS GmbH U.S. Patent 6,599,473 rier. The process proceeds in an adiabatic manner. Liquid test samples are analysed by electrochemilu- The educt mixture can also contain hydrocarbons minescence (EL) using a specific biochemical binding reformed simultaneously with the alcohols. reaction to form a complex which contains a chemi- luminescence marker. The complex is bound to a Preparation of Supported Catalysts magnetic microparticle. Potential is applied to a Pt BASF AG European Appl. 1,328,344 working electrode in a measuring cell to trigger the A supported catalyst (1) is obtained by controlled EL reaction. The light emitted by the marking sub- electroless deposition of a Pt group metal from a stance is measured to determine the concentration of solution containing: (a) a homogeneously dissolved the marked microparticle. compound of Pt group metal(s); (b) a reducing agent; and (c) at least one collagen selected from isopoly Combustible Gas Sensor acids and heteropoly acids of Nb, Ta, Mo, W and V NATL. INST. ADV. IND. TECHNOL. or their salts. (1) is used to hydrogenate inorganic or Japanese Appl. 2003/083,929 organic compounds, especially for synthesis of H2O2. A combustible gas (especially a hydrocarbon-based gas) sensor has a Pt and a Au electrode formed in Hydrocarbon Synthesis in a Three-Phase Reactor parallel on the same face of a solid electrolyte body INST. FRANCAIS DU PETROLE World Appl. 03/044,126 with proton conductivity, held at 250–450°C in con- Hydrocarbons are synthesised from a mixture com- tact with an atmosphere to be measured. When gas is prising CO and H2, and optionally CO2, in the present, a potential difference is generated across the presence of a supported catalyst (1) containing at electrodes, and its value is a measure of the gas con- least one Group VIII metal, such as Ru. The support centration. Combustible gas, excluding H, CO and comprises ZrO2 or a mixed ZrO2-Al2O3, the ZrO2 NO, can be detected with satisfactory sensitivity being in quadratic and/or amorphous form. (1) is without being dependent on steam. used in the liquid phase in a three-phase reactor.

Platinum Metals Rev., 2003, 47, (4), 188–190 188 Microspheroidal Palladium-Gold Catalysts HOMOGENEOUS CATALYSIS BP CHEMICALS LTD World Appl. 03/061,829 A catalyst active for the fluid bed acetoxylation of Manufacture of Trimethylhydroquinone Diacylates World Appl. 03/051,812 ethylene to produce vinyl acetate is prepared by ROCHE VITAMINS AG A 2,3,5-trimethylhydroquinone diacylate (1) is pro- impregnating microspheroidal catalyst support parti- duced by reacting ketoisophorone with an acylating cles of SiO , Al O , ZrO or their mixtures, with an 2 2 3 2 agent, such as an acid anhydride, etc., in the presence aqueous solution of Pd and Au compounds, by the of a NH- or CH-acidic catalyst, such as bis(perfluori- incipient wetness technique, while agitating the sup- nated hydrocarbyl sulfonyl) imides and Rh, Pd, Pt, B, port particles. The Pd compound is an acetate, sulfate, Mg, Al, etc., salts; and tris(perfluoroalkanesulfonyl or nitrate, chloride, or contains halogen; and the Au pentafluorobenzenesulfonyl) methanes and metal compound is a chloride, dimethyl Au acetate, etc.; salts. (1) can be converted into (all-rac)-a-tocopherol, both may include their Group I and II salts. The the most active vitamin E, by transesterification. impregnated support particles are then dried. Surfactant Compounds from Polyols Treatment of Industrial Organic Pollutants CNRS World Appl. 03/053,987 CNRS World Appl. 03/064,333 Surfactant compounds (1) are produced by reacting Industrial effluent containing organic pollutants is a pentose with an alkadiene in the presence of a Pd treated by ozonation in a reactor in the presence of a catalyst activated by a phosphine in the presence of a Ru and/or Ir catalyst supported on CeO2, ZrO2, TiO2 tertiary amine. The reaction can be carried out in or their mixtures. The catalyst is made from powder aqueous medium or in a polar organic solvent. (1) particles 20–500 µm in size, maintained in suspen- obtained in aqueous medium mostly contain pentose sion. The effluent treated with the ozone and the mono(alkadienyl) ethers, whereas in organic medium catalyst are continuously fed through a separation (1) mostly contain pentose di(alkadienyl) ethers. system to separate the catalyst; the part of the efflu- ent free of catalyst is removed while the remainder is recycled with the catalyst back into the reactor. Osmium-Assisted Oxidative Cleavage of Olefins MICHIGAN STATE UNIV. U.S. Appl. 2003/0,149,299 Oxidative cleavage of oxidisable organic compounds . Treating Diesel Exhaust Gases is performed using an OsO4, OsCl3 or K2OsO4 2H2O FORD GLOBAL TECHNOL. INC U.S. Appl. 2003/0,140,620 catalyst, and a peroxy compound such as peroxy- A diesel exhaust treatment system and a method to monosulfuric acid and its salts. Selective production oxidise NO to NO2 at low temperatures uses a first of aldehydes, carboxylic acids, esters, or ketones from catalyst of Pt/ZrO2-stabilised SiO2 (1), pretreated at the corresponding mono-, 1,1-di-, 1,2-di-, tri- or 500–650ºC in a NO-O2-N2 mixture. A sufficient tetra-substituted olefins proceeds with fewer prob- amount of NO2 is used to oxidise particulate matter lems than with the ozonolysis method. Aldehydes trapped on a particulate filter. (1) can also include can be oxidised alone or with the Os in an interactive TiO2, P2O5, WO3, etc., or a heteropolyacid to increase solvent to produce an ester or a carboxylic acid. activity or decrease the Pt loading. A second catalyst for selective reduction is downstream of the filter. Cationic Ruthenium and Osmium Complexes STUDIENGESELLSCHAFT KOHLE mbH Deeply Reduced Oxidation Catalyst U.S. Patent 6,590,048 MONSANTO TECHNOLOGY LLC U.S. Patent 6,603,039 Highly active cationic vinylidene, allenylidene and N-(Phosphonomethyl)glycerine is formed by con- higher cumulenylidene complexes of Ru or Os are tacting N-(phosphonomethyl)iminodiacetic acid or its prepared and used as catalysts (1) or catalyst precur- salt with an oxidation catalyst (1) in a solution or slur- sors (2) for olefin metathesis reactions. (1) and (2) are ry of pH < 7, under O2. (1) increases the oxidation of stable and exhibit high catalytic activity and good formaldehyde and formic acid byproducts into CO2 compatibility with functional groups, solvents, H2O and H2O. (1) comprises 0.5–20% of Pt, Pd, Ru, Rh, Ir, and additives, without need for further activation. Os, Ag and/or Au, and a promoter of 0.5–10% of Bi, Olefins of all types can be used as the substrates in Pb, Sn, etc., supported on C. (1) improves resistance RCM of acyclic dienes and polyenes, the metathesis to noble metal leaching, and is used in liquid phase of enynes and dienynes, ROMP of cyclic olefins, etc. oxidation reactions, especially in an acidic oxidative environment or in those that solubilise noble metals. Producing Ketals and/or Acetals MITSUBISHI CHEM. CORP Japanese Appl. 2003/081,901 Platinum in Carbon Fibre Dehydrogenation Catalyst A ketal and/or an acetal (1) are produced by oxidis- TOYOTA MOTOR CORP Japanese Appl. 2003/088,756 ing olefins, containing ethylenic double bond(s), with

Pressurised CO2 is pumped into a pressure resistant O2 and an alcohol in the presence of a Pd catalyst. After container holding activated C fibre and Pt acetylacet- recovering the reaction products, an alcohol solution onate (1) dissolved in auxiliary solvent. On heating, containing the catalyst is reused, while maintaining

CO2 becomes supercritical and dissolves (1) which the moisture content £ 20 wt.%. (1) are produced in diffuses into the pores of the C fibre. This improves high selectivity, and deposition of a catalyst compo- the catalyst efficiency to remove H from a hydride. nent when olefins are oxidised with O2 is suppressed.

Platinum Metals Rev., 2003, 47, (4) 189 FUEL CELLS One-Step Deposition for FeRAM TEXAS INSTRUMENTS INC U.S. Patent 6,576,482 Thermal Regulating Catalyst Composition A one-step method to deposit successive layers of a 2003/0,144,133 PLUG POWER INC U.S. Appl. transition metal Al oxynitride and a transition metal A thermal regulating composition used as a catalyst Al nitride over a substrate by sputter deposition, system in a fuel processor for a fuel cell includes Pt, using a transition metal/Al target in a N -containing Pd, Rh, Ru, Ir, Cu, Ni, Fe, Cr, Zn or Co, as a catalyst, 2 atmosphere is claimed. In another one-step method, and a zeolite, SiO , Al O or a clay, as a desiccant (1). 2 2 3 the top electrode, such as an Ir/IrO, and diffusion (1) can sorb and desorb a heat transfer material, such barrier layer, and a hard mask layer are formed using as water, so as to remove part of the heat generated two sputter deposition chambers, one with an Ir tar- when the metal undergoes an exothermic reaction. get and another with a TiAl target. A hard mask layer and upper diffusion barrier layer for the capacitor Fuel Cell with Internal Thermally Integrated Reformer stack of a FeRAM can be deposited. GENCELL CORP U.S. Patent 6,602,626 An apparatus for autothermal reforming hydrocar- bon fuel in a fuel cell stack includes a plurality of fuel Etching Platinum Using a Silicon Carbide Mask APPLIED MATERIALS INC U.S. Patent 6,579,796 cells stacked together. Each fuel cell has an inlet man- Pt is etched using a SiC mask (1) by providing an ifold, and all are aligned to form a chamber. A wand etch stack including a patterned SiC layer overlying a of porous, ceramic Al2O3 supporting a deposited Pt, layer of Pt, then pattern etching the Pt layer using a Pd, Ru or Ni catalyst extends through the manifold. plasma generated from a source gas of Cl2, BCl3 and A mixing device is positioned within the wand and a nonreactive, diluent gas. (1) can be deposited and carries fuel gas and oxidant throughout the wand. patterned using standard techniques, and can be easi- ly removed without damaging either the Pt or an Fuel Cell Generating Element underlying doped substrate material. A smooth Pt TOSHIBA INT. FUEL CELLS CORP etch profile and an etch profile angle of about 75–90º 2003/086,192 Japanese Appl. are obtained. Methods of forming semiconductor The generating element of a fuel cell comprises a structures useful in the preparation of DRAM and fuel electrode; a catalyst/oxide/polymer electrolyte FeRAM cells are also disclosed. thin layer of a surface-modified oxide selected from: oxides or from a SO3H group, a COOH group, a PO H group or an OH group; and a metal catalyst Magnetic Recording Media with High SNR 3 SEAGATE TECHNOLOGY LLC U.S. Patent 6,596,341 layer of Pt, Pd, Rh and/or Ir on a C powder or fibre Magnetic recording media (1) are produced by sput- used as the oxidant electrode; with an electrolyte ter depositing a magnetic alloy overlayer of Co and Pt polymer membrane between. The performance of the onto a nonmagnetic underlayer. Thermally unstable fuel cell increases by preventing the permeation of the small grains are eliminated by heating at 150–600ºC. fuel, such as H2 or MeOH, to the oxidant. A layer of nonferromagnetic Cr, Mn or Ta is deposit- ed, and then heated to diffuse into the grain ELECTRICAL AND ELECTRONIC boundaries of the heat-treated magnetic alloy layer. (1) has particular applicability to a high area density ENGINEERING magnetic recording media exhibiting high coercivity Laminated Magnetic Recording Media and thermal stability. IBM CORP World Appl. 03/065,356 A laminated magnetic recording medium (1) for data Elastic Electric Contact storage has an antiferromagnetically coupled layer (2) , TAIKO DENKI CO LTD Japanese Appl. 2003/124,396 made of Ru, Rh, Ir, Cr, Cu and their alloys, and a sin- An elastic electric contact (1) is composed of an gle ferromagnetic layer separated by a nonferro- elastic member by forming Si into a semi-spherical magnetic spacer layer (3). (2) is formed as two ferro- shape and a conductive band-like film composed of a magnetic films coupled across an antiferromagnet- head, a body and an extended part integrally formed ically coupling film of composition and thickness to from Pd and Ti. The head is formed from a lower induce antiferromagnetic coupling. Layer (3) prevents layer and a Au plating upper layer. (1) has a longer ser- antiferromagnetic exchange coupling. (1) has better vice life and provides reliable electrical connection. thermal stability and less intrinsic media noise.

Magnetoresistive Memory Cell Structures MEDICAL USES T. ZHU et al. U.S. Appl. 2003/0,147,273 Novel, Water-Soluble, Antitumour Porphyrins A magnetoresistive memory structure with superior ZENTARIS AG World Appl. 03/064,424 selectivity has cells with two pinned magnetic layers, Novel, H2O-soluble porphyrin Pt compounds of formed with antiparallel magnetisation orientation the tetraarylporphyrin Pt derivatives type or the (net magnetic moment is 0), on one side of a free hematoporphyrin Pt derivatives type with high magnetic layer separated by a Ru layer. More pre- tumour selectivity are synthesised and their cytotoxi- dictable switching behaviour and increased write city obtained. The compounds are particularly selectivity of the memory cells are obtained. suitable for photodynamic antitumour therapy.

Platinum Metals Rev., 2003, 47, (4) 190 NAME INDEX TO VOLUME 47

Page Page Page Page Aaltonen, T. 133 Barnard, C. F. J. 109 Cemalovic, S. 89 Davies, N. A. 136 Acciari, H. A. 187 Barrera, G. D. 38 Cerecetto, H. 87 Davies, P. R. 120 Adesida, I. 89 Barry, C. G. 92 Cv ermák, J. 32, 166 Davis, M. J. 132 Aemmer, T. 39 Bartlett, P. N. 72 Chang, J.-H. 132 Day, C. S. 92 Ager, D. J. 134 Baselt, D. R. 89 Chang, Y. 186 de Bruijn, F. A. 91 Aguirre, P. 40 Bashkin, I. O. 166 Chayahara, A. 38 de Miguel, Y. R. 89 Aharon, A. 31 Beckman, E. J. 134 Chen, S.-A. 60 de Souza, J. P. I. 40 Ahmed, M. O. 60 Bedford, R. B. 91 Chen, W. X. 40 De Vita, A. 98 Ahmed, R. 91 Bell, S. E. J. 32 Chen, X. 60 Dedeev, A. V. 59 Ahn, K.-S. 136 Beller, M. 39 Chen, X. Y. 185 Demel, S. 186 Ainge, D. 91 Bennani, Y. L. 174 Chistov, E. M. 166 Dempsey, N. M. 132 Akiyama, R. 174 Bergamaski, K. 40 Cho, S.-H. 187 D’Epifanio, A. 184 Alapieti, T. T. 59 Bergman, R. G. 132 Choe, S.-B. 37 Di Pietro, C. 38 Alén, P. 133 Bertagnolli, H. 88 Choi, J.-H. 136, 187 Dias, E. 134 Allardyce, C. S. 136 Betts, A. J. 131 Chuang, K. T. 39 Díaz, D. J. 89 Alper, H. 40 Bierbach, U. 92 Ciuparu, D. 90 Dickinson, J. M. 91 Alsters, P. L. 185 Biggs, T. 142 Cloumann, A. 166 Dmitriev, V. A. 36 Alstrum-Acevedo, Birtill, J. 13 Cochran, R. N. 134 Dogan, A. 88 J. H. 19 Bitner, T. W. 89 Cole, J. M. 89 Dowling, D. P. 131 Altman, E. 90 Blake, M. E. 91 Cole-Hamilton, Dragojlovic, V. 135 Amberg, W. 174 Bohn, P. W. 89 D. J. 14, 91 Dubenskyy, V. 184 An, W. 39 Bonard, J.-M. 187 Collella, W. 31 Dunn, B. 59 Anderson, J. 14 Boudvillain, M. 92 Collier, P. J. 110 Dyomina, S. V. 166 Anderson, R. 185 Bowker, M. 13 Colombi Ciacchi, Dyson, P. J. 136 Anishchenko, A. A. 166 Boxall, D. L. 187 L. 98 Antane, S. 186 Boyes, E. D. 110 Conway, B. E. 88 Ebitani, K. 40 Antebi, S. 40 Breen, J. P. 39 Coppens, P. 89 Eichler, A. 132 Antolini, E. 187 Brennaman, M. K. 19 Corn, J. D. 187 El Abed, A. 132 Antonov, V. E. 166 Bridger, G. J. 136 Cornell, A. 133 Ellena, J. A. 87 Arakawa, H. 38 Brintzinger, H.-H. 88 Cornely, J. 135 Ellis, D. J. 136 Arblaster, J. W. 167, 174 Britton, C. L. 89 Cornish, L. A. 142 Eloy, R. 131 Arnaud, M. N. 131 Bronstein, L. 185 Cortie, M. B. 142 Endo, K. 187 Artemenko, Yu. A. 119 Bryant, D. E. 135 Costa, M. 91 Endou, K. 90 Arya, P. 40 Buchanan, D. L. 59 Cozzi, P. G. 186 Ermakov, A. V. 36 Asadullah, M. 39 Burch, R. 39 Crabtree, R. H. 73, 184 Ermilin, V. N. 166 Asakura, S. 187 Butts, C. P. 91 Crispini, A. 38 Evans, C. 184 Ashton, S. V. 19, 36, Crispino, G. A. 174, 186 58, 87, 121, 156 Cabri, L. J. 59 Croce, F. 184 Failes, T. W. 136 Attard, G. A. 39 Camara, G. A. 92 Croiset, E. B. 90 Fairlamb, I. J. S. 91 Avdyukhina, V. M. 166 Cameron, B. R. 136 Fawcett, J. 184 Avilés, T. 91 Cameron, D. S. 28 Dahl, L. F. 132 Fedik, I. I. 166 Azuma, H. 37 Campagna, S. 38 Dalton, L. 38 Feng, M. 185 Cao, C.-N. 88 Danciu, T. 134 Ferguson, I. T. 92 Bach, I. 91 Cao, Y. 89 Daniells, S. T. 39 Ferguson, R. D. 135 Bae, J. W. 90 Carley, A. F. 120 Darkes, M. C. 136 Fermi, E. 168 Bagley, K. A. 89 Carlson, B. 38 Darriet, J. 132 Ferreira, M. 134 Baik, H. K. 187 Carraher, C. E. 109 Datye, A. 90 Feth, M. 88 Baraka, A. M. 38 Castellano, F. N. 133 Davey, P. N. 134 Filippov, G. V. 166 Bard, A. J. 38 Cavell, K. J. 88 Davies, A. T. 134 Finke, R. G. 135

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Fishwick, C. W. G. 186 Gushchin, G. M. 46 Hudgins, R. R. 90 Kano, K. 92 Fleischer, M. 185 Huffman, J. C. 40 Kashiya, V. G. 166 Fleming, C. N. 19 Haber, J. 120 Hughes, R. 134 Kasuga, K. 37 Fondran, J. C. 40 Hai, N. H. 132 Hutchings, G. J. 120 Katayama, E. 40 Fonseca, F. J. 134 Hair, C. M. 134 Kato, H. 58 Foster, D. F. 14 Hajnik, D. M. 134 Ikeda, T. 92 Katoh, R. 38 Fricker, S. P. 136 Håkansson, B. 133 Indolese, A. F. 39 Katona, B. W. 90 Fruhberger, B. 89 Haley, M. M. 37 Inoue, K. 58 Katsnelson, A. A. 166 Fu, X. 183 Hall, M. D. 136 Inoue, S. 58 Kaufman, A. 135 Fujihashi, G. 38 Hambley, T. W. 136 Ishida, T. 174 Kaushik, N. K. 92 Furuya, Y. 132 Hamed, H. A. 38 Islam, A. 38 Keays, R. R. 59 Han, B. 186 Isogawa, S. 38 Keijzer, M. 91 Gabriele, B. 91 Hancu, D. 134 Ito, S. 39 Kelly, G. 134 Gadel’shin, M. Sh. 166 Handa, M. 37 Ito, T. 92 Kenik, E. A. 187 Gai, P. L. 110 Hara, K. 38 Ivanov, S. A. 132 Khatyr, A. 133 Gallezot, P. 13 Hara, Y. 90 Izu, N. 133 Kilner, M. 135 Gambino, D. 87 Hards, G. 30 Kim, C. C. 136 Gao, F. G. 38 Harriman, A. 133 Jackson, S. D. 13 Kim, D.-E. 37 Gao, H. 186 Harris, R. 29 Jackson, P. F. 40 Kim, D.-H. 37 Gao, L. 136 Hartung, J. 174 Jacob, V. 37 Kim, H. 134 Gerisch, M. 132 Havighurst, M. D. 89 James, D. 14 Kim, H.-K. 187 Givord, D. 132 Haxton, K. J. 14 Jang, E. J. 90 Kim, I. G. 90 Giz, M. J. 92 He, Z. 132 Jang, H. W. 136 Kim, J. K. 136 Gladden, L. F. 134 Henderson, W. 184 Jang, J.-S. 92 Kim, S.-J. 132 Glagolev, M. V. 166 Herskowitz, M. 39 Jang, P. 19 Kim, Y.-S. 136 Gloaguen, F. 136 Hickey, M. J. 186 Janssen, G. 30 King, W. D. 187 Goltsov, V. A. 36 Higashijima, M. 88 Jayaraman, S. 107 Kingston, L. P. 186 Goltsova, M. V. 119 Hillier, A. C. 107 Je, J. H. 136 Kiss, G. 185 Golunski, S. E. 120 Hiratsuka, A. 37 Jen, A. K.-Y. 38 Kitano, M. 92 Gonzalez, E. R. 40 Hiroki, T. 88 Jenkins, D. J. 39 Kitauchi, T. 92 González, M. 87 Hiromitsu, I. 92 Jeon, I. C. 88 Kitazawa, M. 38 Goodall, B. L. 40 Hirono, S. 185 Jeon, I.-J. 37 Kiwi-Minsker, L. 39 Goodman, D. W. 120 Hissler, M. 133 Jeong, K.-S. 174 Klaassen, E. 89 Green, M. L. H. 13 Hodgson, D. M. 91 Jewson, J. 134 Klein, A. 88 Greenberg, B. A. 46 Hoffman, E. L. 59 Jiang, T. 186 Kloetzing, R. J. 135 Grey, R. 134 Holder, D. 91 Jiang, X. 38 Klüfers, P. 184 Griffin, K. 185 Hong, S. W. 133 Johnson, B. F. G. 89 Knight, J. G. 90 Griffith, W. P. 175 Horino, H. 37 Johnston, P. 185 Knights, K. A. 89 Grigg, R. 186 Horino, Y. 38 Johnstone, R. A. W. 90 Knochel, P. 135 Grin, Y. 132 Hornstein, B. J. 135 Jollie, D. M. 108 Kobal, I. 37 Grokhovskaya, L. G. 46 Hoshino, M. 133 Jones, J. M. 14 Kobayashi, S. 174 Groß, A. 184 Hou, K. 134 Jones, J. R. 186 Kogan, S. B. 39 Grosso, J. A. 186 Hu, C. T. 37 Josepovits, V. K. 185 Kokalj, A. 37 Grove, D. E. 44 Hu, J.-M. 88 Judkins, C. M. G. 89 Kolarik, Z. 74, 123 Grumett, P. 163 Hu, P. 39 Komarova, M. Z. 60 Grushin, V. V. 132 Hu, X. 111 Kabalka, G. W. 134 Kong, Y. 184 Guasp, E. 186 Hua, S.-N. 184 Kaiser, S. 186 Korzeniewski, C. 136 Guastaldi, A. C. 187 Huang, C.-H. 89 Kaminsky, W. 38 Koterazawa, K. 58 Guerin, S. 72 Huang, J. 186 Kaneda, K. 40 Kovács, K. 185 Gusev, A. L. 166 Huang, W. L. 185 Kang, D.-W. 37 Kovalevsky, A. Yu. 89 Gusev, D. G. 37 Huang, Y.-Q. 92 Kanki, K. 135 Kozhevnikov, I. V. 134

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Kreuer, K.-D. 31 Lyubovsky, M. R. 90 Mizuuchi, K. 58 Park, K.-W. 136, 187 Kruglikov, N. A. 46 Mlsna, T. E. 89 Park, S.-J. 92 Krumper, J. R. 132 Machrouhi, F. 90 Mochizuki, K. 88 Patel, S. V. 89 Kucera, G. L. 92 Maillard, F. 136 Molander, G. A. 90 Pérez-Ruiz, T. 89 Kucernak, A. 30 Manav, N. 92 Molnar, R. J. 89 Peters, E.-M. 132 Kuech, T. F. 136 Mancuso, R. 91 Montilla, F. 91 Peters, K. 132 Kulkarni, G. U. 120 Manorama, S. V. 133 Mori, T. 58 Pfefferle, L. D. 90 Kunimori, K. 39 Mantle, M. D. 134 Mori, W. 88 Phelan, G. D. 38 Kunte, T. 184 Manzer, L. E. 40 Morikawa, K. 174 Pierard, F. Y. T. M. 91 Kuznetsov, V. F. 37 Marrison, L. R. 91 Morris, R. E. 14 Pierozynski, B. 88 Kwiatkowski, K. C. 187 Marshall, W. J. 132 Moya, S. A. 40 Piro, O. E. 87 Kwong, J.-L. 174 Martín, J. 89 Mukhopadhyay, S. 39 Pittelkow, U. 39 Martínez-Lozano, Muraki, Y. 37 Poliakoff, M. 91 Labande, A. H. 91 C. 89 Murata, M. 40 Pollington, S. 13 Lahtinen, J. J. 59 Marty, P. 28 Murata, S. 38 Pomestchenko, I. E. 133 Lai, X. 120 Masuda, T. 135 Murav’yov, L. L. 166 Pompe, W. 98 Lakina, N. 185 Mather, A. N. 186 Murayama, N. 133 Ponyatovsky, E. G. 166 Le Bozec, H. 40 Mathieu, H. J. 187 Murphy, O. J. 187 Pope, C. 131 Lee, C. O. 136 Matsubara, I. 133 Musawir, M. 134 Poulston, S. 13 Lee, C.-W. 92 Matsuda, K. 187 Prakash, I. 134 Lee, J.-L. 136 Matsushima, T. 37 Nah, Y.-C. 136 Presting, H. 166 Lee, J. R. 185 Mattoso, L. H. C. 134 Nakata, E. 88 Puddephatt, R. J. 185 Lee, J. S. 90 Matveeva, V. 185 Namboodiri, V. 134 Lee, J. Y. 40 Maury, F. 133 Nart, F. C. 40 Qafisheh, N. 39 Lee, K. H. 90 McAuley, B. M. 186 Naydenov, V. 90 Qi, Z. 31, 135 Lee, S.-K. 2, 61 McConnell, M. L. 131 Nechaev, Yu. S. 166 Qiu, X.-P. 92 Lee, S.-M. 187 McCorkle, D. 89 Neve, F. 38 Queiroz, S. L. 40 Lee, Y. S. 133 McGuinness, D. S. 88 Nicholson, B. K. 184 Leger, J.-M. 136 McKenzie, A. D. 59 Ning, Y. 111 Rajesh, B. 187 Lesher, C. M. 59 Meade, D. E. 135 Niwa, O. 185 Rao, C. N. R. 120 Leskelä, M. 133 Mednikov, E. G. 132 Noblia, P. 87 Ratner, S. 39 Lewis, F. A. 32, 166 Meier, D. C. 120 Razler, T. 40 Li, J. 186 Meixner, H. 185 Ogura, K. 135 Reale, P. 184 Liang, Y. 58, 60 Meng, H.-M. 88 Ohno, H. 187 Reedijk, J. 92 Liao, J.-L. 60 Menges, F. 186 Ohno, Y. 37 Reinkingh, J. 29 Lindbergh, G. 133 Menzinger, M. 90 Ok, Y.-W. 187 Renard, E. V. 74, 123 Lipian, J. 40 Meriani, S. 98 Oliveira, O. N. 134 Rendulic, K. D. 132 Lippert, B. 92 Merkle, R. K. W. 59 Olsen, M. 136 Renken, A. 39 Liu, C. 89 Mertig, M. 98 Ooe, M. 40 Réti, F. 185 Liu, J.-Y. 90 Meyer, T. J. 19 Ostrick, B. 185 Revkevich, G. P. 166 Liu, R. 91 Middleman, E. 31 Otero, L. 87 Rhodes, L. F. 40 Liu, S. 38 Mikuriya, M. 37 Ozeki, N. 135 Rickert, K. A. 136 Liu, Y.-C. 92 Mills, A. 2, 61 Ritala, M. 133 Liu, Z. 40 Mimna, R. A. 40 Paganin, V. A. 92 Riul, A. 134 Lockley, W. J. S. 186 Miscoria, S. A. 38 Pagni, R. M. 134 Rivas, G. A. 38 Lotz, M. 135 Mitchell, C. J. 185 Papageorgopoulos, Roberts, M. W. 120 Lough, A. J. 37 Miyazaki, Y. 133 D. C. 91 Rodionova, L. A. 46 Lu, L. 90 Miyazawa, M. 135 Papanikolas, J. M. 19 Roh, J. S. 187 Lu, T.-M. 185 Miyazawa, T. 39 Pardey, A. J. 40 Ropartz, L. 14 Lukehart, C. M. 187 Mizugaki, T. 40 Park, J.-W. 133 Rosa, V. 91 Luman, C. R. 133 Mizuno, N. 27 Park, K.-C. 133 Rose, D. J. 136

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Roshan, N. R. 166 Slugovc, C. 186 Tong, X. Q. 32 Wilson, M. T. 136 Roudgar, A. 184 Smith, M. D. 132 Tosheva, L. 90 Witcomb, M. J. 142 Roy, D. 134 Smith, R. A. 135 Tseng, H.-E. 60 Wohnrath, K. 134 Royo, E. 88 Smotkin, E. S. 91 Tseng, M. C. 185 Wolfrath, O. 39 Ruck, M. 184 Sohn, Y. S. 136 Tsujimura, S. 92 Wollaston, W. H. 175 Ruettinger, W. 29 Söhnel, T. 184 Turney, E. C. 92 Wong, K. M.-C. 185 Rzez ¢ nicka, I. 37 Sollid, K. 166 Twigg, M. V. 15, 157 Woods, P. J. 168 Song, R. 136 Wu, G.-S. 92 Sachtler, W. M. H. 120 Spannenberg, A. 39 Uozumi, Y. 60 Wu, J. 184 Sadakane, M. 88 Spencer, M. S. 120 Urawa, Y. 135 Wu, W. 186 Sakhanskaya, I. N. 46 Spernat, A. 39 Salerno, G. 91 Spiridonov, B. A. 166 Valetsky, P. 185 Xanthopoulos, N. 187 Salter, P. A. 136 Spivak, L. V. 166 van Boom, J. H. 92 Xu, D. 174 Saluta, G. 92 Sridharan, V. 186 van der Marel, G. A. 92 Xu, Z. 135 Sanger, A. R. 39 Stelzer, F. 186 Vandyshev, A. B. 166 Santos, M. L. 187 Sterte, J. 90 Vaz, L.-M. 91 Yam, V. W.-W. 185 Sariego, R. 40 Stitzer, K. E. 132 Vedeneev, A. I. 166 Yamada, M. 39 Sasson, Y. 39 Stock, S. R. 187 Veldhuis, J. B. J. 91 Yamaguchi, K. 27 Schennach, R. 132 Strauss, S. H. 89 Vercik, L. C. O. 187 Yamashita, K. 40 Schmidt, K. S. 92 Stromnova, T. A. 20 Verdier, M. 132 Yanagida, M. 38 Schnyder, A. 39 Studer, M. 39 Veron, M. 132 Yandulov, D. 40 Schoefberger, W. 186 Su Ham, L. M. 135 Vijayaraghavan, G. 136 Yang, G.-R. 185 Schwartz, A. 92 Su, L. 89 Vinod, C. P. 120 Yang, W. 89 Scopelliti, R. 136 Su, N. 135 Virica, J. 186 Yates, B. F. 88 Scott, K. 31 Sugihara, H. 38 Vishwanathan, B. 187 Yee, H. 136 Scrosati, B. 184 Sulman, E. 185 Vlasov, N. M. 166 Yoon, B. 134 Sellin, M. F. 91 Sun, M. 90 Vokoun, D. 37 Yoon, D. S. 187 Selman, R. 28 Sung, Y.-E. 136, 187 Volkov, A. Yu. 46 Yoon, Y. S. 187 Selvakumar, K. 39 Suzuki, H. 133 von Schnering, You, T. 185 Senkevich, J. J. 185 H. G. 132 Yuan, M. 89 Senocq, F. 133 Tachibana, Y. 38 Seong, T.-Y. 92, 187 Tagawa, T. 37, 58 Wada, T. 37, 58 Zaitsev, V. I. 119 Settimi, L. 184 Takagi, K. 40 Wagner, F. R. 132 Zapf, A. 39 Shaarawy, H. H. 38 Takamizawa, S. 88 Wai, C. M. 134 Zhang, J. 88 Sharpless, K. B. 174 Tannenbaum, R. 37 Wang, L. 134 Zhang, J.-Q. 88 Shelishch, B. 166 Taya, M. 37, 58 Wang, S. 186 Zhang, S.-Y. 184 Shibata, T. 40 Tchabanenko, K. 90 Wang, X. 183 Zhang, W. 183 Shick, R. A. 40 Tenhuisen, K. 186 Wang, Z.-M. 174 Zhang, X.-L. 174 Shin, S.-C. 37 Tennant, S. 175 Warmack, B. 89 Zhang, X.-Y. 184 Shin, W. 133 Thampi, K. R. 187 Weakley, T. J. R. 37 Zhang, Y.-M. 40 Shinto, R. 92 Thiele, G. 132 Webster, J. M. 91 Zhang, Z.-S. 184 Sidorov, A. 185 Thomas, J. M. 120 Wei, I-Y. 89 Zhao, G. 186 Sidorov, S. 185 Tian, Q. 184 Wei, R. 186 Zhirov, G. I. 119 Siegmann-Louda, Ticianelli, E. A. 92 White, K. W. P. 27, 72, Zhou, J. 132 D. W. 109 Tilley, T. D. 132 121, 131, 174 Zhu, N. 185 Silveston, P. L. 90 Timofeyev, N. I. 36 White, P. 14, 58, 60, 107, Zhu, W. 89 Singh, A. 186 Toda, A. 38 119, 122, 183 Zhu, W.-T. 92 Skerlj, R. T. 136 Tojo, H. 38 Whittaker, D. 90 Ziessel, R. 133 Skryabina, N. E. 166 Tomás, V. 89 Wilkins, A. J. J. 96, 140 Zink, J. I. 89 Slawin, A. M. Z. 14 Tomishige, K. 39 Wilkinson, D. J. 186 Zubieta, J. 136 Slovetsky, D. I. 166 Tomita, M. 185 Williamson, T. L. 89 zur Loye, H.-C. 132

Platinum Metals Rev., 2003, 47, (4) 194 SUBJECT INDEX TO VOLUME 47

Page Page a = abstract CO2, production, in benzene photodegradation 183 Acetoxylation, oxidative, of alkenes 20 solvent, a 91, 134 Acetylcholine, sensor, a 185 Carbonylation, iodoarenes, a 40 Acetylenes, phenyl-, living polymerisation, a 135 oxidative, amines, a 91 terminal, Sonogashira couplings, a 91 RuCl3·3H2O, to Ru carbonyls, a 37 Actuators, shape memory alloys 58 5-vinyloxazolidin-2-ones, a 90 Air, photocatalytic purification 61 Carbonyls, Pd(+1) clusters, as catalysts 20 + Alcohols, dehydration 20 [Rh(CO)4] , luminescence, a 89 ethyl, electrooxidation, a 40 Ru, from RuCl3·3H2O, a 37 in fuel cells 28 Carboxylic Acids, aryl, thermolysis of Pd4(CO)4(OAc)4 20 methyl, adsorption, desorption, a 132 from alcohols, a 185 electrooxidation, a 40, 92, 136, 187 hydrogenation, a 90 oxidation 27, 134, 135 Catalysis, book reviews 110, 120 selective 20, 185 in CO2 solvent, a 91, 134 Aldehydes, from alcohols, a 134, 185 conferences 13, 28 oxidation, a 135 electron microscopy, use of 110 Alkanes, dehydrogenation 13, 39 in H2O solvent 60, 174 oxidation 20 heterogeneous, a 39, 90, 134, 185–186 Alkenes, acetoxylation, alkoxylation, oxidative 20 history 175 from alkanes, a 39 homogeneous, a 39–40, 90–91, 134–135, 186 from alkynes 44 surface chemistry 120 hydroformylation 14, 91, 135 Catalysts, agglomeration 44 hydrogenation, a 90, 134, 135 deactivation 13, 44 oxidation 20, 135 metal loss 44 Alkoxylation, oxidative, of alkenes 20 model 120 Alkylation, asymmetric, 1,3-diphenylallylic systems, a 135 pgm, supported single crystals 120 Alkynes, intramolecular couplings, a 40 poisoning, chemical, physical 44 oxidation, a 135 recycling 13, 39, 134, 186 reduction 44 SelectraTM Shift, for reformer 28 Alloys, dental, a 187 spent, precious metal recovery 163 mechanical properties 46, 111 three-way, see Three-Way Catalysts Amination, amino ester + aryl bromides, a 186 Catalysts, Iridium, Ir, in lean-burn gasoline engine 157 Amines, carbonylation, oxidative, a 91 Ir/SrTiO3, H2O photocleavage 2 Amino Acids, aromatic, reduction, a 134 Ir/TiO2, H2O photooxidation 2 Pt clusters, growth 98 Ir(0) nanoclusters, cyclohexene hydrogenation, a 135 Ammonia, oxidation 36, 111 Catalysts, Iridium Complexes, cyclooctadienylIr(I) reaction with NO, a 39 hexafluoropentanedionate, D labelling, a 186 Antibacterial Agents, Ag/Pt coated polymers 131 Ir-HetPHOX, asymmetric hydrogenations, a 186 Antimicrobial Agents, Ru(II)-arenes, a 136 IrCl(CO)(PPh3)2, alkyne–alkyne couplings, a 40 Antisense Drugs, trans-PtII-modified PNA oligomers, a 92 Vaska’s complex, alkyne–alkyne couplings, a 40 â AquaCat , pgm recovery, from spent catalysts 163 Catalysts, Osmium, Os/SrTiO3, H2O photocleavage 2 Arenes, iodo-, carbonylation, a 40 Catalysts, Osmium Complexes, OsO4/polymer 174 oxidation, a 135 PVI-Os(dpa)2Cl, with diaphorase, a 92 Aryl Halides, coupling reactions, a 39, 90, 91, 134, 135, 186 Catalysts, Palladium, APK-2/a-Al2O3, NOx conversion 20 Aryl Triflates, Suzuki-Miyaura couplings, a 90 electrocatalysts, PtPd/C 28, 91 Arylation, intramolecular, of pyrimidines, a 40 Lindlar’s catalyst, reduction of alkynes 44 Aryldiazonium Salts, cross-coupling reactions, a 39 palladised metal(IV) phosphates, hydrogenations, a 90 Autocatalysts 13, 15, 20, 96, 140, 157 Pd, HC emission oxidation 157 nanostructured, in pellistor sensors 72 Benzene, photodegradation 183 supported, CH4 combustion, a 90 Biomass, gasification, a 39 Pd clusters/Sibunit, hydrocarbon oxidation 20 Biphenyls, by coupling, of substituted halobenzenes, a 39 Pd clusters/spherical SiO2 particles, CO, HC, oxidation 20 Book Reviews, “Electron Microscopy in Heterogeneous Pd nanoparticles, hydrogenation of olefins, a 134, 186 Catalysis” 110 phen protected, a 186 ‘Polymeric platinum-containing drugs in the treatment Pd powder,+KF/Al2O3, solventless Suzuki coupling, a 134 of cancer’ 109 Pd-Cu/C, thermal treatments 110 “Surface Chemistry and Catalysis” 120 Pd-Fe, dehalogenation of trihalomethanes, a 186 “The Geology, Geochemistry, Mineralogy and Mineral Pd-zeolite beta spheres, preparation, a 90 Beneficiation of Platinum-Group Elements” 59 Pd/Al2O3, CH4 combustion, S poisoning 13 sintering mechanisms 110 Cancer, anti-, pgm complexes 92, 109, 136 Pd/C, + NaCl, for debenzylation, a 186 Capacitors, HD memory, RuTiN diffusion barrier, a 187 spent, Pd recovery 163 microsuper-, RuO2 electrode, W-RuO2 electrode, a 187 + tetrabutylammonium bromide, biphenyl synthesis, a 39 Pd alloy powders 36 Pd/CaCO3 + Pb, reduction of alkynes 44 Carbenes 37, 39, 73, 88, 184 Pd/Rh, TWC, high thermal durability 15 Carbon Oxides, CO, adsorption energy, a 184 Pd/SrTiO3, H2O photocleavage 2 CO/H2 mixtures, oxidation, a 90 Pd/Ti silicalite, synthesis of propylene oxide, a 134 for intramolecular alkyne–alkyne couplings, a 40 Pd/TiO2, H2O photoreduction 2 oxidation 20 H2O purification 61 poisoning, in PEMFC 107 STM studies 13 sensors, a 89, 185 Pd4(CO)4(OCOR)4 + bipy/oxide carrier, oxidations 20 tolerance, in PEMFC, a 91 NOx reduction, by CH4 20

Platinum Metals Rev., 2003, 47, (4), 195–200 195 Page Page Catalysts, Palladium, (cont.) Catalysts, Platinum, (cont.) Pd4(CO)4(OCOR)4 + phen/a-Al2O3, NOx conversion 20 spent, Pt recovery 163 Pd4(CO)4(OCOR)4 + phen/oxide carrier, oxidations 20 Pt/fluorinated C, NO + NH3, a 39 NOx reduction, by CH4 20 Pt/Pd/Rh, TWC, pgm loading 157 Pt/Pd/Rh, TWC, pgm loading 157 Pt/polypyrrole, electrooxidation of MeOH, a 187 TiO2-Pd(II) chloride 61 Pt/Rh, TWC, high thermal durability 15 3 Catalysts, Palladium Complexes, (h -allyl)Pd, addition Pt/‘RuO2’/TiO2, H2O photocleavage 2 polymerisation of norbornene-type monomers, a 40 Pt/‘RuO2’/TiO2 doped with Cr, H2O photocleavage 2 monocarbenepalladium(0), coupling reactions, a 39 Pt/SiO2, hydrogenation, of ethene, ethyne, a 134 Na{Pd4[CpMo(CO)3]4}, dehydration of alcohols 20 Pt/Sn/Al2O3 filaments, a 39 PAMAM dendrimer-Pd(RCN)2Cl2/SiO2, -Pd(tetra- Pt/SrTiO3, H2O photocleavage 2 methylethylenediamine)Me2/SiO2, a 40 Pt/TiO2, air purification 61 Pd(+1) carbonyl clusters, oxidations 20 benzene photodegradation, magnetic field effects 183 Pd with P,N-ferrocenyl ligands, allylic alkylation, a 135 H2O, photocleavage, photoreduction, purification 2, 61 Pd-dendrimer nanocomposites, olefin hydrogenation, a 40 Pt/TiO2/SiO2, H2O photoreduction 2 Pd-phosphine-PS-PEG resin, reactions in H2O60Pt/WO3, H2O photooxidation 2 Pd/C + PPh3, Sonogashira coupling, a 91 Ru, Pt/C, oxidation of alcohols, a 185 t Pd2(dba)3/BINAP/NaO Bu, coupling amination, a 186 TiO2-Pt(IV) chloride, H2O purification 61 Pd4(CO)4(OCOR)4/bipy, /phen, olefin oxidation 20 Catalysts, Rhodium, autocatalysts, NOx reduction 13, 157 PdCl2/HP(adamantyl)2, /HP(t-butyl)2, Heck reactions, a 39 Pd/Rh, TWC, high thermal durability 15 PdCl2(dppf), Suzuki coupling, solid phase, a 135 Pt-Rh/SiO2, heat treatment; under N2 110 PdCl2(dppf)·CH2Cl2/Cs2CO3, S.-M. coupling, a 90 Pt/Pd/Rh, TWC, pgm loading 157 PdCl2(PPh3)2, preparation of d-lactam, a 90 Pt/Rh, TWC, high thermal durability 15 Suzuki-Miyaura coupling, a 135 PtRh, EtOH electrooxidation, a 40 PdI2 + KI, oxidative carbonylation of amines, a 91 Rh, EtOH electrooxidation, a 40 Pd(OAc)2, in TBAB-H2O, Suzuki coupling, a 91 Rh/Al2O3, CH4 combustion, S poisoning 13 Pd(OAc)2 + NBu3/P(o-tolyl)3, Heck reaction, a 91 reduction of aromatic amino acid derivatives, a 134 Pd(OAc)2/PPh3, Sonogashira coupling, a 91 Rh/C, reduction of aromatic amino acid derivatives, a 134 Pd(OAc)2/PPh3/NEt4Cl/K2CO3, cyclisations, a 186 Rh/CeO2/SiO2, biomass gasification, a 39 Pd(OAc)2/PPh3/TlOAc, cyclisations, a 186 Rh/TiO2, H2O, photooxidation, photoreduction 2 Pd(OAc)2(PPh3)2 + base, arylation, intramolecular, a 40 STM studies 13 Pd(PPh3)4, Sonogashira coupling, a 91 Rh/WO3, H2O photooxidation 2 removal, by polymer-bound ethylenediamines, a 135 TiO2-Rh(III) chloride 61 Catalysts, Platinum, electrocatalysts, nanoparticles, Catalysts, Rhodium Complexes, [(cod)RhL¢Cl] 73 Pt, on C, for DMFC, a 40 [(nbd)RhCl]2/Ph2C=C(Ph)Li/Ph3P, polymerisation, a 135 Pt, on C, Ru deposition, MeOH oxidation, a 136 Rh with P,N-ferrocenyl ligands, hydroboration, a 135 Pt, on polypyrrole nanotubules, for fuel cells a 187 Rh POSS dendrimers, oct-1-ene hydroformylation 14 Pt, Pt-Ru, spheres, on C 28 [Rh2(OAc)4]/phosphines, hydroformylation in sc-CO2, a 91 Pt, for fuel cells 28, 40, 135, 136, 187 Rh2[(R)-DDBNP]4, Rh2[(S)-DOSP]4, a 91 3+ Pt/carbon-CH2CH2PO3H2, for PEMFCs, a 135 Rh(bpy)3 /TiO2, H2O photoreduction 2 Pt, + Cr, Fe, Mn, Mo, Pd, for fuel cells 28 [RhCl(cod)]2, alkyne–alkyne couplings, a 40 Pt/Ni, for DMFCs, a 187 [Rh(L-L)NBD]BF4/Nafion, hydroformylation, a 135 PtPd4/C, for PEMFCs, a 91 [Rh(L)2NBD]BF4/Nafion, hydroformylation, a 135 PtRh, EtOH electrooxidation, a 40 Catalysts, Ruthenium, Cu-Ru/C, CO, H2 treatments 110 PtRu, for fuel cells 28, 92, 107, 136, 187 electrocatalysts, PtRu, for fuel cells 28, 92, 107, 136, 187 PtRuMo, for PEMFCs, reactivity imaging 107 PtRuMo, for PEMFCs, reactivity imaging 107 Pt-Ru-P/C nanocomposites, anodes, for DMFCs, a 187 Ru-Se, for fuel cells 28 HPS-Pt-THF, direct L-sorbose oxidation, a 185 Pt-Ru-Sn/active C, hydrogenation of carboxylic acids, a 90 platinised metal(IV) phosphates, hydrogenations, a 90 Pt/‘RuO2’/TiO2, H2O photocleavage 2 Pt, addition, Ru-Sn/active C, hydrogenations, a 90 Pt/‘RuO2’/TiO2 doped with Cr, H2O photocleavage 2 in autocatalysts, emission control: diesel, gasoline, Ru, Pt/C, oxidation of alcohols, a 185 lean-burn gasoline 15, 157 RuIV-CoIII oxide, oxidation of alcohols, a 134 filter, aldehydes, CO, HC conversion, from diesel 157 Ru-Sn/active C, hydrogenation of carboxylic acids, a 90 ceramic foam, PM removal, from diesel emissions 157 Ru/Al2O3, oxidation of alcohols 27 PM, from diesel emissions 15, 157 Ru/C cathode, electroreduction of N2, a 184 HC + NOx 157 with Pt, hydrogenation of glucose to sorbitol 13 oxidation, CO, HC, NO 157 Ru/SrTiO3, H2O photocleavage 2 MeOH, a 136 Ru/TiO2, H2O photooxidation 2 NOx-traps 15, 157 oxidation of organic pollutants, in H2O13 with Ru/C, hydrogenation of glucose to sorbitol 13 Ru/WO3, H2O photooxidation 2 Pt, Bi/C, N2O decomposition, a 39 ‘RuO2’/BaTi4O9, H2O photocleavage 2 Pt, Bi/C, 1-octanol to octanoic acid, a 185 ‘RuO2’/In1–xNixTaO4, H2O photocleavage 2 2-octanol to 2-octanone, a 185 RuO2/WO3, H2O photooxidation 2 Pt-Rh/SiO2, heat treatment; under N2 110 RuO2·xH2O/WO3, H2O photooxidation 2 Pt-Ru-Sn/active C, hydrogenations, a 90 Catalysts, Ruthenium Complexes, Grubbs catalysts, a 186 Pt-Sn-K/, Pt-Sn-K-Fe/Al2O3, dehydrogenations, a 39 Ru benzylidenes, ROMP, a 186 Pt–WOx, MeOH oxidation, a 136 Ru bipy, Ru phen, WGSR, a 40 Pt/Al2O3, butane dehydrogenation 13 RuO4, oxidations, in dimethyl carbonate-H2O, a 135 TM CCl4 hydrodechlorination, a 90 CCRT , for diesel emission control 15, 157 CH4 combustion, S poisoning 13 Cerium, addition to, Pt-Pd-Rh, mechanical properties 111 sintering mechanisms 110 Chagas’ Disease, Ru complexes 87 Pt/Al2O3-coated monolith, oxidation of CO/H2, a 90 Chemical Vapour Deposition, macroporous films, a 185 Pt/B/TiO2, H2O photocleavage 2 Chemiluminescence, see Luminescence Pt/Ba + Rh, NOx storage/reduction 13 Chlorate, electrolysis, a 133 Pt/C, N2O decomposition, a 39 Choline, sensor, a 185

Platinum Metals Rev., 2003, 47, (4) 196 Page Page Chromatography, Pd, Rh, Ru 123 Electrodes, (cont.) CHTTM, for gasoline emission control 15, 157 in fuel cells, see Fuel Cells 2+ Clusters, Pd(+1) carbonyls, as catalysts 20 [Os(bpy)2(bpy-(CH2)13SH)] /Au, with ascorbic acid, a 88 Pd, nucleation and growth, on biopolymers 98 with dopamine, a 88 4+ [PdBi10] , a 184 Pd/C, anode, in electroreduction of N2, a 184 Pt, nucleation and growth, on biopolymers 98 Pt nanoparticles, embedded, in C film, a 185 in solution 98 Ru-based DSAâ, chlorate electrolysis, a 133 [Ru5C(CO)15], gas sensor activity, a 89 Ru/C, cathode, in electroreduction of N2, a 184 Coatings, Ag/Pt, on polymers, antibacterial activity 131 RuO2, W-RuO2, in microsupercapacitors, a 187 Ir-Re, by plasma-based ion implantation, a 38 Ti/IrO2-TaO5, microstructure, a 88 Pd-Ni, for microcantilevers, in H2 sensor, a 89 Electroless Plating, Pd, on a-Al2O3, a 134 Pt, for cantilevers, in scanning microscopy probes, a 38 on TiN barrier films, for electroless Cu, a 133 see also Deposition and Electrodeposition Electrolysis, chlorate, a 133 Combinatorial Chemistry, fuel cell cataysts 107 Emission Control, motor vehicles 13, 15, 96, 140, 157 Suzuki couplings, a 135 Etching, Pt ultrathin films, a 89 use of K alkenyltrifluoroborates, a 90 Ethers, oxidation, a 135 Combustion, CH4 13, 90 Conferences, 4th Noble and Rare Metals: NRM-2003, Films, Pd, on Au single crystals, a 184 Donetsk, Ukraine, 2003 36 nanostructured 72 8th Grove Fuel Cell Symposium, London, 2003 31 Pt, Pt-Pd, macroporous, by CVD, a 185 Catalyst Life Cycle, University of Bath, U.K., 2002 13 Ru b-diketonato polypyridyls on TiO2, a 38 Fuel Cells – Science and Technology 2002, see also Thin Films Amsterdam, 2002 28 ‘Final Analysis’ 44, 96, 140 Hannover Messe, Hydrogen + Fuel Cells, 2003 108 Foils, Fe/Pt, a 132 IFSSEHT-2003, Sarov, Russia, 2003 166 Fracture, brittle, in Ir, Ir alloys 36 SAE, Detroit, U.S.A. 15, 157 in Pt-Pd-Rh alloys, Ce addition, Ru addition 111 Coupling Reactions 39, 40, 73, 186 Fuel Cells, a 40, 91–92, 135–136, 187 see also Heck Reactions and Suzuki Couplings bio-, anodes, a 92 Creep, -rupture curves, Pt-Pd-Rh, + Ce, + Ru 111 catalysts, Pt nanoparticles/C, + Ru deposition, a 136 CRTTM, for diesel emission control 15, 96, 157 Pt/C, PtRu/C, MeOH electrochemical oxidation, a 136 Cyclisation, to pyrazolidines, a 186 conferences 28, 31, 108 Cyclometallates, Pd phenylbipyridines, luminescence, a 38 direct 2-propanol fuel cell 28 L-Cysteine, determination of, a 89 DMFC, anodes, Pt-Ru/, Pt-Ru-P/C, nanocomposites, a 187 L-Cystine, determination of, a 89 cathode, Ru-Se 28 electrocatalysts, high throughput screening, a 91 Debenzylation, in synthesis of quinolinones, a 186 Pt/polypyrrole, a 187 Decomposition, N2O, a 39 Pt nanoparticles/polypyrrole nanotubules, a 187 Dehalogenation, trihalomethanes, a 186 Pt/Ni, a 187 Dehydration, alcohols 20 Pt-Ru/mesocarbon microbead support, a 92 Dehydrogenation, alkanes 13, 39 electrodes, a 40 Dendrimers, as catalysts 14, 40 MEAs, a 91 Dental, alloys, a 187 electrodes, Pt, Pt–WOx, MeOH oxidation, a 136 Deoxymannojirimycin, synthesis, a 90 fuel, H2 28, 108, 119, 166 Deposition, Pd, on dielectric surfaces, a 185 low temperature, electrocatalysts, Pt/C, a 187 see also Coatings and Electrodeposition MCFC, with gas turbines 28 Deuterium, interaction with Pd, Pd alloys 166 membrane electrode assemblies 28, 91 labelling, anilines, benzylamines, N heterocycles, a 186 nanoparticles 28, 40, 136, 187 Diacyls, from thermolysis of Pd4(CO)4(OCOR)4 20 PEMFC, CO poisoning 107 Diesel, particulate filters, for emissions control 15, 96, 157 CO tolerance, a 91 PM, control, by CCRTTM 15, 157 electrocatalysts, Pt, Pt alloys 28, 135 by CRTTM 15, 96, 157 Pt nanoparticles/polypyrrole nanotubules, a 187 TM by EGR-CRT 157 Pt/carbon-CH2CH2PO3H2, a 135 TM by SCRT 157 PtPd4/C, a 91 S content 96 PtRu, PtRuMo, reactivity imaging 107 Dihydroxylation, asymmetric, olefins 174 Pt-Ru/C, a 92 Dispersion Hardening, of alloys, for glass production 36 electrodes, Pt 107, 108 Displacive Transformations, Pt alloys 142 MEAs 28 DNA, Pt clusters, growth 98 as power sources, for camcorder 108 for fork-lift truck 108 EGR-CRTTM, for diesel emission control 157 for public transport 108 Electrical Contacts, ohmic, Pd/Ru/p-GaN, a 92 for video camera 108 Pt, on p-GaN, a 136 SOFC, with gas turbines 28 Electrochemistry, a 88, 133, 184 oximes, on Pt(100) surfaces, on Pt(111) surfaces, a 88 Gasification, biomass, a 39 III 5– [SiW11O39Ru (H2O)] , a 88 Gasoline, S content 96 IV III 11– [SiW11O39Ru ORu SiW11O39] , a 88 Gauzes, NH3 oxidation 36, 111 Electrodeposition, Pd, codeposition of H, a 89 Geology, book 59 films, nanostructured, on Si 72 Glass, production, using dispersion hardened alloys 36 on Ni, a 89 Glucose, hydrogenation 13 Rh, on Ti substrates, a 38 sensors, a 38, 185 see also Coatings and Deposition Gorsky Effect, on H diffusion coefficients, in Pd77Ag23 32 Electrodeposition and Surface Coatings, a38, 89, 133, 185 Electrodes, C paste, Ir, + Cu, Pd, Ru, Heck Reactions, a 39, 91 in glucose sensor, a 38 Heterocycles, synthesis, a 40 FePO4, + RuO2, for Li cells, a 184 High Throughput Screening, fuel cell catalysts 91, 107

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History, Enrico Fermi 167 Langmuir-Bodgett Films, conducting polymer/Ru3+, a 134 Ir isotopes, discoverers 167 Lasers, welding, of dental alloys, a 187 Pd discovery, uses 175 LEDs, Os bpy, Ru bpy, Ru phen, a 38 2+ Rh discovery, uses 175 Luminescence, chemi-, Ru(bipy)3 , a 89 Smithson Tennant 175 cyclometallated Pd(II) complexes, a 38 + William Hyde Wollaston, Wollaston Medal 175 [Ir(pik)(phen)Cl2] , a 185 Hydroboration, styrene, with catechol borane, a 135 Pt(II) terpyridyl-capped C-rich molecular rods, a 185 + Hydrocarbons, emission control 15, 96, 157 [Rh(CO)4] , [Rh(CO)4](1-Et-CB11F11), a 89 hydrogenation, a 134 Ru(II) poly(pyridine)s, a 133 oxidation 20 reforming 28, 108 Magnetism, Co/Pt nanomultilayers, properties, a 37 Hydrodechlorination, CCl4, a 90 effects, on benzene photodegradation 183 Hydroformylation, alkenes 14, 91, 135 D-Mannolactam, synthesis, a 90 Hydrogen, atomic, adsorption energy, a 184 Mass Spectrometry, Ru complexes, + PS, + PP, a 88 by photocleavage, photoreduction, of H2O2MEAs, array, high throughput screening, a 91 CO/H2 mixtures, oxidation, a 90 in fuel cells 28 codeposited, in Pd electrodeposition, a 89 Mechanical Properties, CoPt, FePd, NiPt, Pd3Fe, Pt3Co 46 diffusion coefficents, in Pd77Ag23 membranes 32 Pt-Pd-Rh, + Ce, + Ru 111 economy 166 Medical Uses 87, 92, 109, 136, 187 electrooxidation, a 187 Membranes, Pd, H2 permeation 32 extraction 166 Pd alloys, H2 permeation 32, 166 fuel, for fuel cells 28, 108, 119, 166 Pd-Cu, Pd-Y, Pd-In-Ru, H extraction 166 interaction, with Pd, Pd alloys, Pt, Pt alloys, Rh 166 Pd/Ag, reactor, microstructured filament catalyst, a 39 with Pd, hydride phases, video studies 119 Pd/Ag on a-Al2O3, for H separation, a 134 purification 32 Pd77Ag23, hydrogen diffusion coefficients 32 safety 166 Pd/Si, Pt/Si, for H separation 166 sensors 89, 166 Memory, capacitors, a 187 separation, from gases 134, 166 Metallabenzenes, platinabenzene, synthesis, a 37 transport 166 Methane, combustion 13, 90 Hydrogen Peroxide, electrooxidation, a 185 in NOx reduction 20 sensor, a 185 sensor 72 Hydrogen Sulfide, sensor, a 89 Microscopy, electron, in heterogeneous catalysis 110 Hydrogenation, alkenes, a 90, 134, 135 Microwaves, to prepare, aryl isonipecotic acids, a 186 asymmetric, imines, olefins, a 186 Pt nanoparticles/C, a 40 carboxylic acids, a 90 in solventless Suzuki couplings, a 134 ethyne, a 134 MOCVD, Ir thin films, a 133 glucose 13 hydrocarbons, a 134 NADH, electrochemical oxidation, a 92 olefins, a 40, 134, 186 Nanocomposites, Pt-Ru/, Pt-Ru-P/C, electrocatalysts, a 187 Nanomultilayers, Co/Pt, magnetic anisotropy, a 37 Imines, hydrogenation, asymmetric, a 186 Nanoparticles, Pd, phen protected, a 186 Ion Exchange, Pd ions, Rh ions, Ru ions 74, 123 Pt, embedded, in C film electrode, a 185 Ionic Liquids, solvents, a 186 Pt, fuel cell electrocatalysts 28, 40, 136, 187 Iridium, brittle fracture 36 Nanostructures, LB film, conducting polymer + Ru3+, a 134 for C paste electrodes, a 38 Pd films 72 Ir(110), N2O dissociation, a 37 Pd30-, Pd54-core, nanosized, synthesis, a 132 isotopes, history of the discoveries 167 Nitric Acid, manufacture 111 thin films, by MOCVD, a 133 Nitrogen, adsorption, Rh(II) benzoate pyrazine, a 88 Iridium Alloys, brittle fracture 36 desorption, from Ir(110), Pd(110), Rh(110), a 37 Ir-Re coatings, by plasma-based ion implantation, a 38 electroreduction, a 184 Iridium Complexes, cyclometallation-induced formation Nitrogen Oxides, NO, reaction with NH3, a 39 of M–C bonds to sp2 C of aryl and vinyl groups 73 scavengers, Ru(III) polyaminocarboxylates, a 136 Ir carbenes 73, 184 NOx, catalytic control systems 15, 157 Ir(COD)(MeCp), for MOCVD, a 133 in PM combustion 15, 157 + [Ir(pik)(phen)Cl2] , luminescence, a 185 reduction, by CH4 20 K[Ir(pik)Cl4], spectral properties, a 185 selective catalytic reduction of diesel emissions 157 phosphorescence 60, 89 storage/reduction 13 Iridium Compounds, electrodes, a 88 -traps 15, 96, 157 Isocyanides, for alkyne–alkyne couplings, a 40 N2O, decomposition, a 39 Isomerism, coordination, M(II) salicylhydroxamates, a 184 dissociation, on Ir(110), Pd(110), Rh(110), a 37 Isotopes, detector, double-sided silicon strip 167 Nitrosoarenes, reaction with Pd4(CO)4(OCOR)4 20 Ir, discoveries 167 Nuclear Waste, HLLWs, recovery, of Pd, Rh, Ru 74, 123 Jewellery, Pt, Pt alloys 36 Ohmic Contacts, see Electrical Contacts Johnson Matthey, AquaCatâ 163 Oils, engine, additives 140 Catalysts division, ECT, PCT 121 OLEDs, red, Os(II)(N–N)2L–L in PVK/PBD, a 38 emission control, motor vehicles 15, 96, 157 Olefins, asymmetric dihydroxylation 174 FP05 prototype reformer 28 coupling reactions, a 39, 135 “Platinum 2003” 122 hydrogenation, a 40, 134, 186 ‘Platinum Today’ website 121 asymmetric, a 186 Johnson, Percival Norton 175 oxidation 20 Osmium, recovery and separation 36 Ketones, synthesis, a 91, 185 Osmium Complexes, electrodes, a 88 Os bpy, in LEDs, a 38 Labelling, D2, anilines, benzylamines, N heterocycles, a 186 Os(II)(N–N)2L–L, phosphorescence, a 38

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4+ Osmium Compounds, Ba3LiOs2O9, Ba3NaOs2O9, a 132 Palladium Compounds, Bi14PdBr16, [PdBi10] , a 184 Oxidation, alcohols 27, 134, 135 PdO/SnO2, CO sensitivity, a 185 aldehydes, a 135 Patents 41–43, 93–95, 137–139, 188–190 alkanes 20 searching of 156 alkenes 20, 135 Phase Diagrams, Au-Cu-Pd 36 alkynes, a 135 Pt-Al-Ni, -Al-Ru, -Ti-Ni, -Ti-Ru 142 arenes, a 135 Phosphorescence, btp2Ir(acac) 60 CO 20 electro-, Ir p-substituted 2-phenylpyridines, a 89 CO/H2 mixtures, a 90 Ir(ppy)3 60 electro-, EtOH, a 40 Os(II)(N–N)2L–L, a 38 H2, a 187 Pt(II) diimine bis(pyrenylacetylide), a 133 H2O2, a 185 Photocatalysis, benzene degradation 183 MeOH, a 40, 92, 136, 187 by semiconductors 2, 61 electrochemical, NADH, a 92 Photocleavage, semiconductor-sensitised, H2O2 ethers, a 135 Photoconversion, a 38, 89, 133, 185 hydrocarbons 20 Os bpy, a 38 4+ NH3 36, 111 [Rh(NH3)5L] , a 92 olefins 20 Ru bpy, Ru phen, a 38 2+ organic pollutants, in H2O13[Ru(bpy)2dppz] , light-switch effect 19 selective, alcohols 20, 185 Ru b-diketonato polypyridyls on TiO2, a 38 L-sorbose, a 185 Photoluminescence, see Luminescence unsaturated compounds 20 Photolysis, laser, Rh(III) porphyrins, a 133 using supercritical H2O, of spent catalysts 163 Photomineralisation, organic pollutants, a 61 Oxygen, by photocleavage, photooxidation, of H2O2Photooxidation, semiconductor-sensitised, of H2O2 sensors, a 133 Photoproperties, chloro-pgm-, chloro-Pt(IV)-titania 61 + [Ir(pik)(phen)Cl2] , K[Ir(pik)Cl4], a 185 Palladium, addition to, Mg-Ni, for H storage 28 pgm/TiO2, pgm oxide/TiO2 2, 61 II deposition, on dielectric surfaces, a 185 trans-[Ru (NH3)4(SO2)X]Y, isomerisation of SO2, a 89 discovery, history 175 Photoreactions, semiconductor-sensitised 2 electrodeposition 72, 89 Photoreduction, semiconductor-sensitised, of H2O2 electrodes, a 38, 184 Photosensitisation, semiconductors 2 in fuel cells, see Fuel Cells Photovoltaic Cell, Pt/C60/In/Al, a 92 electroless plating, a 133, 134 Plasma, ion implantation, of Ir-Re coatings, a 38 films, for CH4 detection 72 Plasma Technology, ‘PM-plasmoceramic’ system 36 hydride phases, video studies 119 “Platinum 2003” 122 interaction with D2, interaction with H2 166 Platinum, Ag/Pt coated polymers, antibacterial activity 131 membranes 32 in CeO2 O2 sensors, a 133 overlayers, on Au single crystals, a 184 coatings, for scanning microscopy probes, a 38 palladised, Co oxide, Mn oxide, interaction with H2 166 electrical contacts, Pt, on p-GaN, a 136 Pd/Ru/p-GaN ohmic contacts, a 92 electrodes, in fuel cells, see Fuel Cells Pd(110), N2O dissociation, a 37 films, macroporous, by CVD, a 185 Pd(111), MeOH adsorption, MeOH desorption, a 132 interaction with H2 166 recovery, from nuclear waste 74, 123 isotopes 174 from spent catalysts 163 jewellery 36 Palladium Alloys, Au-Cu-Pd, phase diagrams 36 membranes 166 Bi2Pd, intermetallic phase, a 184 nanoparticles 28, 40, 136, 185, 187 capacitors 36 photovoltaic cell, a 92 dental, Pd-Ag-Cu-Au, a 187 Pt(100), Pt(111), reactivity of oximes, a 88 interaction with D2, interaction with H2 166 recovery, from spent catalysts 163 mechanical properties, FePd, Pd3Fe 46 ultrathin films, a 89 Pt-Pd-Rh, + Ce, + Ru 111 Platinum Alloys, Co/Pt nanomultilayers, magnetism, a 37 membranes 32, 39, 134, 166 Fe/Pt foils, a 132 Pd-Ni, coatings, for microcantilevers, in H2 sensor, a 89 interaction with H2 166 Pd/V, MeOH adsorption, MeOH desorption, a 132 jewellery 36 Pt-Pd films, macroporous, by CVD, a 185 mechanical properties, CoPt, NiPt, Pt3Co 46 shape memory effect, Fe-Pd 37, 58 Pt-Pd-Rh, + Ce, + Ru 111 Fe-Pd-Pt, a 37 nanoparticles 28 TiPdNi, a 184 Pt-Al, -Al-Ni, -Al-Ru, -Cr, -Cu, -Fe, -Ga, -Mn, -Ti, Palladium Complexes, BINAP(O) Pd, synthesis, a 132 -Ti-Ni, -Ti-Ru, -V 142 clusters, nucleation and growth, on biopolymers 98 Pt-Pd films, macroporous, by CVD, a 185 [(COD)PdMe(L)]n+, synthesis, a 88 shape memory effect, Fe-Pd-Pt, a 37 [(COD)PdMe(OH)], hydrolysis reactions, a 88 Pt3Al, PtFe3, PtTi, (Pt, Ni)Ti 142 Me-PdII N-heterocyclic, germylenes, silylenes, a 88 Platinum Complexes, cationic porphyrin-Pt, cancer, a 136 Na2{Pd4[CpMo(CO)3]4}, synthesis 20 clusters, nucleation, growth, on biopolymers, + [(µ-OH){(COD)PdMe}2] , hydrolysis reactions, a 88 in solution 98 Pd carbenes, a 39, 88, 184 dimers, trimers, formation 98 [Pd4(CO)2L4]X4, L = bipy, phen, synthesis 20 platinabenzene, synthesis, from [Pt(cod)Cl2], a 37 Pd4(CO)4(OAc)4, Pd4(CO)4(OCOR)4, synthesis 20 polymeric, anticancer drugs, anticancer prodrugs 109 [Pd30(CO)26(PEt3)10], [Pd54(CO)40(PEt3)14], nano core, a 132 Pt amine hydroxamates, biological activity, a 136 II [Pd(C4H7)(hfac)], [Pd(hfac)2], in CVD, a 185 trans-Pt -modified PNA oligomers, antisense drugs, a 92 II Pd (hfac)2, + reduced S-terminated silanes, a 185 Pt(II) diimine pyrenylacetylide, phosphorescence, a 133 [Pd(HL)Cl2], HL = thiohydrazone derivatives, a 92 Pt(II) salicylhydroxamates, coordination isomerism, a 184 Pd(II), with reducing sugars, a 184 Pt(II) terpyridyl-capped C-rich molecular rods, a 185 Pd(II) salicylhydroxamates, coordination isomerism, a 184 [Pt(L)2Cl2], HL = thiohydrazone derivatives, a 92 [Pd(Ln)Cl], Ln = bipy derivatives, luminescence, a 38 [PtMe2(COD)], precusor for CVD, a 185

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Platinum Compounds, K2PtCl4, reduction 98 Ruthenium Alloys, (cont.) Pt6Cl12, structure and bonding, a 132 RuTa, shape memory effect, a 132 PtO/SnO2, CO sensitivity, a 185 Ruthenium Complexes, luminescence, a 89, 133 Platinum Group Elements, geology book 59 photoconversion 19, 38 PLEDs, Ir phenylpyridines 60, 89 photoproperties, a 89 Pollution Control, in AquaCatâ process 163 + PP, + PS, in mass spectrometry, a 88 dehalogenation of trihalomethanes, a 186 Ru carbene, chiral, a 37 off-gas, from metallurgical, petrochemical plants 20 Ru carbonyls, by carbonylation of RuCl3·3H2O, a 37 organics, oxidative degradation, a 135 [RuCl2(p-cymene)]2, reaction with diphosphine, a 37 II semiconductor photocatalysis, of air, H2O 13, 61 [Ru Cl2(DMSO)2semicarbazone], Chagas’ disease 87 see also Emission Control mer-[RuCl3(dppb)(py)], in LB films, a 134 Polymerisation, living, of phenylacetylenes, a 135 RuCp2, for atomic layer deposition, a 133 ROMP, a 186 Ru(II)-arenes, antimicrobial properties, a 136 vinyl addition, of norbornene-type monomers, a 40 Ru(III) polyaminocarboxylates, NO scavengers, a 136 Polymers, with Ag/Pt coatings, antibacterial activity 131 Ruthenium Compounds, electrodes, a 184, 187 bio-, nucleation sites, for Pd clusters, Pt clusters 98 [Ru5C(CO)15], gas sensor activity, a 89 -bound ethylenediamines, Pd removal, a 135 RuCl3·3H2O, carbonylation, a 37 III 5– IV III 11– conducting, + mer-[RuCl3(dppb)(py)], LB films, a 134 [SiW11O39Ru (H2O)] , [SiW11O39Ru ORu SiW11O39] , a 88 conjugated star polymers, star block copolymers, a 135 from norbornenedicarboxylic acid ester, by ROMP, a 186 Schottky Barriers, Pt/C60 interface, a 92 TM polypropylene, + (RuC5Me5)3H5, MS, a 88 SCRT , for diesel emission control 157 polypyrrole nanotubules, Pt support, electrocatalysts, a 187 Selective Catalytic Reduction, NOx 157 polystyrene, + [Ru(C5H5)(NCCH3)3][PF6], MS, a 88 Semiconductors, photosensitisation 2, 61 Pt-containing, as anticancer drugs, prodrugs 109 Sensitisers, visible light, chloro-pgm-titania 2, 61 Precipitation, Pd, Rh, Ru 74, 123 Sensors, acetylcholine, choline, a 185 Probes, with Pt coating, scanning probe microscopy, a 38 CH4 72 Propylene Oxide, synthesis, a 134 CO, a 89, 185 Pyrochemistry, Pd, Rh, Ru 74, 123 glucose, a 38, 185 Pyrones, alkenylmethyl-, alkynylmethyl-, synthesis, a 91 H2 89, 166 H2O2, a 185 Quinolinones, synthesis, a 186 H2S, a 89 O2, a 133 Reactors, fixed bed catayst, Pd-zeolite beta spheres, a 90 pellistor 72 fluidised bed continuous feeding, a 39 SO2, a 89 membrane, microstructured by filamentous catalyst, a 39 taste: HCl, NaCl, quinine, sucrose, a 134 Recovery, Os 36 Shape Memory Effect, Fe-Pd 37, 58 Pd, Pt, Rh, from spent catalysts 163 Fe-Pd-Pt, a 37 Pd, Rh, Ru, from nuclear waste 74, 123 Pt3Al, PtFe3, PtTi, (Pt, Ni)Ti 142 Reduction, alkynes 44 RuTa, a 132 aromatic amino acid derivatives, a 134 TiPdNi, a 184 chemical, Pd(II), Rh(III), Ru(IV) 74 Single Crystals, Ba3LiOs2O9, Ba3NaOs2O9, a 132 electrochemical, Pd(II) 74, 123 Solvent Extraction, Pd, Rh, Ru 74, 123 electro-, N2, a 184 Sonogashira Couplings, a 91 NOx 20 Sorbitol, from glucose 13 Refining, Rh 36 L-Sorbose, oxidation, a 185 Reforming, H2 generation, for fuel cells 28, 108 Sputtering, Ir-Re coatings, a 38 Rhodium, discovery, history 175 Pt ultrathin films, a 89 electrodeposition, on Ti substrates, a 38 Sugars, Pd(II) complexes, a 184 interaction with H2 166 Sulfur, in diesel, gasoline 96 recovery, from nuclear waste 74, 123 Sulfur Oxides, SO2, sensor, a 89 from spent catalysts 163 Superelastic Properties, TiPdNi, a 184 refining 36 Suzuki Couplings, a 39, 91, 134, 135 Rh(110), N2O dissociation, a 37 Suzuki-Miyaura Couplings, a 90, 135 Rhodium Bicentenary Competition winner, research 73 Rhodium Alloys, Pt-Pd-Rh, + Ce, + Ru 111 Thermolysis, Pd4(CO)4(OCOR)4 20 Rhodium Complexes, luminescence, a 89 Thin Films, Ir, by MOCVD, a 133 Rh carbenes 73, 184 Ru, by atomic layer deposition, a 133 Rh(II), Rh(III), with bis(oxazoline) pincer ligands, a 132 ultra-, Pt, on porous GaN, electroless etching, a 89 [Rh2(O2CPh)4(pyz)]¥, N2 adsorption, a 88 see also Films Rh(II) trifluoroacetamidate, with 4,4¢-bipy, 1,4-diaza- Three-Way Catalysts 13, 15, 96, 157 bicyclo[2.2.2]octane, pyrazine, as polymers, a 37 Titanium, substrates, for electrodeposition of Rh, a 38 4+ [Rh(NH3)5L] , photocytotoxic agent, a 92 TiO2, deposition, of pgms, pgm oxides 2, 61 – III (X )(PPh3)Rh -OEP, -TPP, laser photolysis, a 133 Trihalomethanes, dehalogenation, a 186 ROMP, norbornenedicarboxylic acid ester, a 186 Ruthenium, addition to, Mg-Ni, for H storage 28 Ureas, from amines, a 91 Pt-Pd-Rh, mechanical properties 111 electrodes, a 38, 133, 184 5-Vinyloxazolidin-2-ones, carbonylation, a 90 in fuel cells, see Fuel Cells VOCs, destruction, by semiconductor photocatalysis 61 Pd/Ru/p-GaN ohmic contacts, a 92 recovery, from nuclear waste 74, 123 Water, oxidation, photocleavage, photoreduction 2 RuTiN, as diffusion barrier, in memory capacitors, a 187 photocatalytic purification 61 thin films, by atomic layer deposition, a 133 as solvent, for catalytic reactions 60, 174 Ruthenium Alloys, membranes 166 supercritical, oxidation, of spent catalysts 163 nanoparticles 28 Water Gas Shift Reaction 28, 40 Pt-Al-Ru, Pt-Ti-Ru 142 Welding, laser, of dental alloys, a 187

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